Error with completion-at-point on empty space

[greghendershott]

1. Enable debug-on-error.
2. In a racket-mode buffer. put point on a blank space, not immediately following some symbol-like text.
3. M-x completion-at-point.

Expected result: Nothing happens.

Result: A *Backtrace* buffer with:

Debugger entered--Lisp error: (invalid-regexp "Regular expression too big")
  all-completions("" (#("in-syntax" 0 9 (racket-module "racket/sequence")) #("file->syntax" 0 12 (racket-module "syntax.rkt")) #("path->existing-syntax" 0 21 (racket-module "syntax.rkt")) #("path->existing-expanded-syntax" 0 30 (racket-module "syntax.rkt")) #("file->expanded-syntax" 0 21 (racket-module "syntax.rkt")) #("make-caching-load/use-compiled-handler" 0 38 (racket-module "syntax.rkt")) #("string->expanded-syntax" 0 23 (racket-module "syntax.rkt")) #("~s" 0 2 (racket-module "racket/format")) #("~e" 0 2 (racket-module "racket/format")) #("~v" 0 2 (racket-module "racket/format")) #("~a" 0 2 (racket-module "racket/format")) #("~r" 0 2 (racket-module "racket/format")) #("~.v" 0 3 (racket-module "racket/format")) #("~.a" 0 3 (racket-module "racket/format")) #("~.s" 0 3 (racket-module "racket/format")) #("blame-swapped?" 0 14 (racket-module "racket/contract")) #("struct/c" 0 8 (racket-module "racket/contract")) #("build-compound-type-name" 0 24 (racket-module "racket/contract")) #("procedure-arity-includes/c" 0 26 (racket-module "racket/contract")) #("unsupplied-arg?" 0 15 (racket-module "racket/contract")) #("list*of" 0 7 (racket-module "racket/contract")) #("struct/dc" 0 9 (racket-module "racket/contract")) #("recontract-out" 0 14 (racket-module "racket/contract")) #("flat-contract-property?" 0 23 (racket-module "racket/contract")) #("blame-add-cdr-context" 0 21 (racket-module "racket/contract")) #("continuation-mark-key/c" 0 23 (racket-module "racket/contract")) #("*list/c" 0 7 (racket-module "racket/contract")) #("any" 0 3 (racket-module "racket/contract")) #("bad-number-of-results" 0 21 (racket-module "racket/contract")) #("exn:fail:contract:blame-object" 0 30 (racket-module "racket/contract")) #("coerce-flat-contract" 0 20 (racket-module "racket/contract")) #("prop:blame" 0 10 (racket-module "racket/contract")) #("char-in" 0 7 (racket-module "racket/contract")) #("flat-murec-contract" 0 19 (racket-module "racket/contract")) #("parametric->/c" 0 14 (racket-module "racket/contract")) #("flat-named-contract" 0 19 (racket-module "racket/contract")) #("flat-rec-contract" 0 17 (racket-module "racket/contract")) #("struct:arrow-contract-info" 0 26 (racket-module "racket/contract")) #("contract-exercise" 0 17 (racket-module "racket/contract")) #("opt/c" 0 5 (racket-module "racket/contract")) #("blame-negative" 0 14 (racket-module "racket/contract")) #("define/contract" 0 15 (racket-module "racket/contract")) #("base->-rngs/c" 0 13 (racket-module "racket/contract")) #("prop:orc-contract" 0 17 (racket-module "racket/contract")) #("contract-random-generate" 0 24 (racket-module "racket/contract")) #("</c" 0 3 (racket-module "racket/contract")) #("contract-projection" 0 19 (racket-module "racket/contract")) #("blame-replaced-negative?" 0 24 (racket-module "racket/contract")) #("flat-contract?" 0 14 (racket-module "racket/contract")) #("blame-add-missing-party" 0 23 (racket-module "racket/contract")) ...) nil)
  complete-with-action(t (#("in-syntax" 0 9 (racket-module "racket/sequence")) #("file->syntax" 0 12 (racket-module "syntax.rkt")) #("path->existing-syntax" 0 21 (racket-module "syntax.rkt")) #("path->existing-expanded-syntax" 0 30 (racket-module "syntax.rkt")) #("file->expanded-syntax" 0 21 (racket-module "syntax.rkt")) #("make-caching-load/use-compiled-handler" 0 38 (racket-module "syntax.rkt")) #("string->expanded-syntax" 0 23 (racket-module "syntax.rkt")) #("~s" 0 2 (racket-module "racket/format")) #("~e" 0 2 (racket-module "racket/format")) #("~v" 0 2 (racket-module "racket/format")) #("~a" 0 2 (racket-module "racket/format")) #("~r" 0 2 (racket-module "racket/format")) #("~.v" 0 3 (racket-module "racket/format")) #("~.a" 0 3 (racket-module "racket/format")) #("~.s" 0 3 (racket-module "racket/format")) #("blame-swapped?" 0 14 (racket-module "racket/contract")) #("struct/c" 0 8 (racket-module "racket/contract")) #("build-compound-type-name" 0 24 (racket-module "racket/contract")) #("procedure-arity-includes/c" 0 26 (racket-module "racket/contract")) #("unsupplied-arg?" 0 15 (racket-module "racket/contract")) #("list*of" 0 7 (racket-module "racket/contract")) #("struct/dc" 0 9 (racket-module "racket/contract")) #("recontract-out" 0 14 (racket-module "racket/contract")) #("flat-contract-property?" 0 23 (racket-module "racket/contract")) #("blame-add-cdr-context" 0 21 (racket-module "racket/contract")) #("continuation-mark-key/c" 0 23 (racket-module "racket/contract")) #("*list/c" 0 7 (racket-module "racket/contract")) #("any" 0 3 (racket-module "racket/contract")) #("bad-number-of-results" 0 21 (racket-module "racket/contract")) #("exn:fail:contract:blame-object" 0 30 (racket-module "racket/contract")) #("coerce-flat-contract" 0 20 (racket-module "racket/contract")) #("prop:blame" 0 10 (racket-module "racket/contract")) #("char-in" 0 7 (racket-module "racket/contract")) #("flat-murec-contract" 0 19 (racket-module "racket/contract")) #("parametric->/c" 0 14 (racket-module "racket/contract")) #("flat-named-contract" 0 19 (racket-module "racket/contract")) #("flat-rec-contract" 0 17 (racket-module "racket/contract")) #("struct:arrow-contract-info" 0 26 (racket-module "racket/contract")) #("contract-exercise" 0 17 (racket-module "racket/contract")) #("opt/c" 0 5 (racket-module "racket/contract")) #("blame-negative" 0 14 (racket-module "racket/contract")) #("define/contract" 0 15 (racket-module "racket/contract")) #("base->-rngs/c" 0 13 (racket-module "racket/contract")) #("prop:orc-contract" 0 17 (racket-module "racket/contract")) #("contract-random-generate" 0 24 (racket-module "racket/contract")) #("</c" 0 3 (racket-module "racket/contract")) #("contract-projection" 0 19 (racket-module "racket/contract")) #("blame-replaced-negative?" 0 24 (racket-module "racket/contract")) #("flat-contract?" 0 14 (racket-module "racket/contract")) #("blame-add-missing-party" 0 23 (racket-module "racket/contract")) ...) "" nil)
  (let nil (complete-with-action action completions prefix predicate))
  (if (eq action 'metadata) (let nil (cons 'metadata (or metadata (list (cons 'category racket--identifier-category))))) (let nil (complete-with-action action completions prefix predicate)))
  (closure ((metadata (category . racket-identifier) (affixation-function . racket--xp-binding-completion-affixator)) (completions #("in-syntax" 0 9 (racket-module "racket/sequence")) #("file->syntax" 0 12 (racket-module "syntax.rkt")) #("path->existing-syntax" 0 21 (racket-module "syntax.rkt")) #("path->existing-expanded-syntax" 0 30 (racket-module "syntax.rkt")) #("file->expanded-syntax" 0 21 (racket-module "syntax.rkt")) #("make-caching-load/use-compiled-handl..." 0 38 (racket-module "syntax.rkt")) #("string->expanded-syntax" 0 23 (racket-module "syntax.rkt")) #("~s" 0 2 (racket-module "racket/format")) #("~e" 0 2 (racket-module "racket/format")) #("~v" 0 2 (racket-module "racket/format")) #("~a" 0 2 (racket-module "racket/format")) #("~r" 0 2 (racket-module "racket/format")) #("~.v" 0 3 (racket-module "racket/format")) #("~.a" 0 3 (racket-module "racket/format")) #("~.s" 0 3 (racket-module "racket/format")) #("blame-swapped?" 0 14 (racket-module "racket/contract")) #("struct/c" 0 8 (racket-module "racket/contract")) #("build-compound-type-name" 0 24 (racket-module "racket/contract")) #("procedure-arity-includes/c" 0 26 (racket-module "racket/contract")) #("unsupplied-arg?" 0 15 (racket-module "racket/contract")) #("list*of" 0 7 (racket-module "racket/contract")) #("struct/dc" 0 9 (racket-module "racket/contract")) #("recontract-out" 0 14 (racket-module "racket/contract")) #("flat-contract-property?" 0 23 (racket-module "racket/contract")) #("blame-add-cdr-context" 0 21 (racket-module "racket/contract")) #("continuation-mark-key/c" 0 23 (racket-module "racket/contract")) #("*list/c" 0 7 (racket-module "racket/contract")) #("any" 0 3 (racket-module "racket/contract")) #("bad-number-of-results" 0 21 (racket-module "racket/contract")) #("exn:fail:contract:blame-object" 0 30 (racket-module "racket/contract")) #("coerce-flat-contract" 0 20 (racket-module "racket/contract")) #("prop:blame" 0 10 (racket-module "racket/contract")) #("char-in" 0 7 (racket-module "racket/contract")) #("flat-murec-contract" 0 19 (racket-module "racket/contract")) #("parametric->/c" 0 14 (racket-module "racket/contract")) ...)) (prefix predicate action) (if (eq action 'metadata) (let nil (cons 'metadata (or metadata ...))) (let nil (complete-with-action action completions prefix predicate))))("" nil t)
  completion-pcm--all-completions("" (prefix point "\n" any ";" any ";" any " " any "I" any "t" any " " any "i" any "s" any " " any "i" any "m" any "p" any "o" any "r" any "t" any "a" any "n" any "t" any " " any "t" any "o" any " " any "r" any ...) (closure ((metadata (category . racket-identifier) (affixation-function . racket--xp-binding-completion-affixator)) (completions #("in-syntax" 0 9 (racket-module "racket/sequence")) #("file->syntax" 0 12 (racket-module "syntax.rkt")) #("path->existing-syntax" 0 21 (racket-module "syntax.rkt")) #("path->existing-expanded-syntax" 0 30 (racket-module "syntax.rkt")) #("file->expanded-syntax" 0 21 (racket-module "syntax.rkt")) #("make-caching-load/use-compiled-handler" 0 38 (racket-module "syntax.rkt")) #("string->expanded-syntax" 0 23 (racket-module "syntax.rkt")) #("~s" 0 2 (racket-module "racket/format")) #("~e" 0 2 (racket-module "racket/format")) #("~v" 0 2 (racket-module "racket/format")) #("~a" 0 2 (racket-module "racket/format")) #("~r" 0 2 (racket-module "racket/format")) #("~.v" 0 3 (racket-module "racket/format")) #("~.a" 0 3 (racket-module "racket/format")) #("~.s" 0 3 (racket-module "racket/format")) #("blame-swapped?" 0 14 (racket-module "racket/contract")) #("struct/c" 0 8 (racket-module "racket/contract")) #("build-compound-type-name" 0 24 (racket-module "racket/contract")) #("procedure-arity-includes/c" 0 26 (racket-module "racket/contract")) #("unsupplied-arg?" 0 15 (racket-module "racket/contract")) #("list*of" 0 7 (racket-module "racket/contract")) #("struct/dc" 0 9 (racket-module "racket/contract")) #("recontract-out" 0 14 (racket-module "racket/contract")) #("flat-contract-property?" 0 23 (racket-module "racket/contract")) #("blame-add-cdr-context" 0 21 (racket-module "racket/contract")) #("continuation-mark-key/c" 0 23 (racket-module "racket/contract")) #("*list/c" 0 7 (racket-module "racket/contract")) #("any" 0 3 (racket-module "racket/contract")) #("bad-number-of-results" 0 21 (racket-module "racket/contract")) #("exn:fail:contract:blame-object" 0 30 (racket-module "racket/contract")) #("coerce-flat-contract" 0 20 (racket-module "racket/contract")) #("prop:blame" 0 10 (racket-module "racket/contract")) #("char-in" 0 7 (racket-module "racket/contract")) #("flat-murec-contract" 0 19 (racket-module "racket/contract")) #("parametric->/c" 0 14 (racket-module "racket/contract")) #("flat-named-contract" 0 19 (racket-module "racket/contract")) #("flat-rec-contract" 0 17 (racket-module "racket/contract")) #("struct:arrow-contract-info" 0 26 (racket-module "racket/contract")) #("contract-exercise" 0 17 (racket-module "racket/contract")) #("opt/c" 0 5 (racket-module "racket/contract")) #("blame-negative" 0 14 (racket-module "racket/contract")) #("define/contract" 0 15 (racket-module "racket/contract")) #("base->-rngs/c" 0 13 (racket-module "racket/contract")) #("prop:orc-contract" 0 17 (racket-module "racket/contract")) #("contract-random-generate" 0 24 (racket-module "racket/contract")) #("</c" 0 3 (racket-module "racket/contract")) #("contract-projection" 0 19 (racket-module "racket/contract")) #("blame-replaced-negative?" 0 24 (racket-module "racket/contract")) #("flat-contract?" 0 14 (racket-module "racket/contract")) ...)) (prefix predicate action) (if (eq action 'metadata) (let nil (cons 'metadata (or metadata (list (cons ... racket--identifier-category))))) (let nil (complete-with-action action completions prefix predicate)))) nil)
  completion-substring--all-completions("\n;; It is important to run this with the correct p..." (closure ((metadata (category . racket-identifier) (affixation-function . racket--xp-binding-completion-affixator)) (completions #("in-syntax" 0 9 (racket-module "racket/sequence")) #("file->syntax" 0 12 (racket-module "syntax.rkt")) #("path->existing-syntax" 0 21 (racket-module "syntax.rkt")) #("path->existing-expanded-syntax" 0 30 (racket-module "syntax.rkt")) #("file->expanded-syntax" 0 21 (racket-module "syntax.rkt")) #("make-caching-load/use-compiled-handler" 0 38 (racket-module "syntax.rkt")) #("string->expanded-syntax" 0 23 (racket-module "syntax.rkt")) #("~s" 0 2 (racket-module "racket/format")) #("~e" 0 2 (racket-module "racket/format")) #("~v" 0 2 (racket-module "racket/format")) #("~a" 0 2 (racket-module "racket/format")) #("~r" 0 2 (racket-module "racket/format")) #("~.v" 0 3 (racket-module "racket/format")) #("~.a" 0 3 (racket-module "racket/format")) #("~.s" 0 3 (racket-module "racket/format")) #("blame-swapped?" 0 14 (racket-module "racket/contract")) #("struct/c" 0 8 (racket-module "racket/contract")) #("build-compound-type-name" 0 24 (racket-module "racket/contract")) #("procedure-arity-includes/c" 0 26 (racket-module "racket/contract")) #("unsupplied-arg?" 0 15 (racket-module "racket/contract")) #("list*of" 0 7 (racket-module "racket/contract")) #("struct/dc" 0 9 (racket-module "racket/contract")) #("recontract-out" 0 14 (racket-module "racket/contract")) #("flat-contract-property?" 0 23 (racket-module "racket/contract")) #("blame-add-cdr-context" 0 21 (racket-module "racket/contract")) #("continuation-mark-key/c" 0 23 (racket-module "racket/contract")) #("*list/c" 0 7 (racket-module "racket/contract")) #("any" 0 3 (racket-module "racket/contract")) #("bad-number-of-results" 0 21 (racket-module "racket/contract")) #("exn:fail:contract:blame-object" 0 30 (racket-module "racket/contract")) #("coerce-flat-contract" 0 20 (racket-module "racket/contract")) #("prop:blame" 0 10 (racket-module "racket/contract")) #("char-in" 0 7 (racket-module "racket/contract")) #("flat-murec-contract" 0 19 (racket-module "racket/contract")) #("parametric->/c" 0 14 (racket-module "racket/contract")) #("flat-named-contract" 0 19 (racket-module "racket/contract")) #("flat-rec-contract" 0 17 (racket-module "racket/contract")) #("struct:arrow-contract-info" 0 26 (racket-module "racket/contract")) #("contract-exercise" 0 17 (racket-module "racket/contract")) #("opt/c" 0 5 (racket-module "racket/contract")) #("blame-negative" 0 14 (racket-module "racket/contract")) #("define/contract" 0 15 (racket-module "racket/contract")) #("base->-rngs/c" 0 13 (racket-module "racket/contract")) #("prop:orc-contract" 0 17 (racket-module "racket/contract")) #("contract-random-generate" 0 24 (racket-module "racket/contract")) #("</c" 0 3 (racket-module "racket/contract")) #("contract-projection" 0 19 (racket-module "racket/contract")) #("blame-replaced-negative?" 0 24 (racket-module "racket/contract")) #("flat-contract?" 0 14 (racket-module "racket/contract")) ...)) (prefix predicate action) (if (eq action 'metadata) (let nil (cons 'metadata (or metadata (list (cons ... racket--identifier-category))))) (let nil (complete-with-action action completions prefix predicate)))) nil 0 completion-flex--make-flex-pattern)
  completion-flex-try-completion("\n;; It is important to run this with the correct p..." (closure ((metadata (category . racket-identifier) (affixation-function . racket--xp-binding-completion-affixator)) (completions #("in-syntax" 0 9 (racket-module "racket/sequence")) #("file->syntax" 0 12 (racket-module "syntax.rkt")) #("path->existing-syntax" 0 21 (racket-module "syntax.rkt")) #("path->existing-expanded-syntax" 0 30 (racket-module "syntax.rkt")) #("file->expanded-syntax" 0 21 (racket-module "syntax.rkt")) #("make-caching-load/use-compiled-handler" 0 38 (racket-module "syntax.rkt")) #("string->expanded-syntax" 0 23 (racket-module "syntax.rkt")) #("~s" 0 2 (racket-module "racket/format")) #("~e" 0 2 (racket-module "racket/format")) #("~v" 0 2 (racket-module "racket/format")) #("~a" 0 2 (racket-module "racket/format")) #("~r" 0 2 (racket-module "racket/format")) #("~.v" 0 3 (racket-module "racket/format")) #("~.a" 0 3 (racket-module "racket/format")) #("~.s" 0 3 (racket-module "racket/format")) #("blame-swapped?" 0 14 (racket-module "racket/contract")) #("struct/c" 0 8 (racket-module "racket/contract")) #("build-compound-type-name" 0 24 (racket-module "racket/contract")) #("procedure-arity-includes/c" 0 26 (racket-module "racket/contract")) #("unsupplied-arg?" 0 15 (racket-module "racket/contract")) #("list*of" 0 7 (racket-module "racket/contract")) #("struct/dc" 0 9 (racket-module "racket/contract")) #("recontract-out" 0 14 (racket-module "racket/contract")) #("flat-contract-property?" 0 23 (racket-module "racket/contract")) #("blame-add-cdr-context" 0 21 (racket-module "racket/contract")) #("continuation-mark-key/c" 0 23 (racket-module "racket/contract")) #("*list/c" 0 7 (racket-module "racket/contract")) #("any" 0 3 (racket-module "racket/contract")) #("bad-number-of-results" 0 21 (racket-module "racket/contract")) #("exn:fail:contract:blame-object" 0 30 (racket-module "racket/contract")) #("coerce-flat-contract" 0 20 (racket-module "racket/contract")) #("prop:blame" 0 10 (racket-module "racket/contract")) #("char-in" 0 7 (racket-module "racket/contract")) #("flat-murec-contract" 0 19 (racket-module "racket/contract")) #("parametric->/c" 0 14 (racket-module "racket/contract")) #("flat-named-contract" 0 19 (racket-module "racket/contract")) #("flat-rec-contract" 0 17 (racket-module "racket/contract")) #("struct:arrow-contract-info" 0 26 (racket-module "racket/contract")) #("contract-exercise" 0 17 (racket-module "racket/contract")) #("opt/c" 0 5 (racket-module "racket/contract")) #("blame-negative" 0 14 (racket-module "racket/contract")) #("define/contract" 0 15 (racket-module "racket/contract")) #("base->-rngs/c" 0 13 (racket-module "racket/contract")) #("prop:orc-contract" 0 17 (racket-module "racket/contract")) #("contract-random-generate" 0 24 (racket-module "racket/contract")) #("</c" 0 3 (racket-module "racket/contract")) #("contract-projection" 0 19 (racket-module "racket/contract")) #("blame-replaced-negative?" 0 24 (racket-module "racket/contract")) #("flat-contract?" 0 14 (racket-module "racket/contract")) ...)) (prefix predicate action) (if (eq action 'metadata) (let nil (cons 'metadata (or metadata (list (cons ... racket--identifier-category))))) (let nil (complete-with-action action completions prefix predicate)))) nil 0)
  #f(compiled-function (style) #<bytecode -0x14719b01722bbe69>)(flex)
  completion--some(#f(compiled-function (style) #<bytecode -0x14719b01722bbe69>) (basic initials flex))
  completion--nth-completion(1 "\n;; It is important to run this with the correct p..." (closure ((metadata (category . racket-identifier) (affixation-function . racket--xp-binding-completion-affixator)) (completions #("in-syntax" 0 9 (racket-module "racket/sequence")) #("file->syntax" 0 12 (racket-module "syntax.rkt")) #("path->existing-syntax" 0 21 (racket-module "syntax.rkt")) #("path->existing-expanded-syntax" 0 30 (racket-module "syntax.rkt")) #("file->expanded-syntax" 0 21 (racket-module "syntax.rkt")) #("make-caching-load/use-compiled-handler" 0 38 (racket-module "syntax.rkt")) #("string->expanded-syntax" 0 23 (racket-module "syntax.rkt")) #("~s" 0 2 (racket-module "racket/format")) #("~e" 0 2 (racket-module "racket/format")) #("~v" 0 2 (racket-module "racket/format")) #("~a" 0 2 (racket-module "racket/format")) #("~r" 0 2 (racket-module "racket/format")) #("~.v" 0 3 (racket-module "racket/format")) #("~.a" 0 3 (racket-module "racket/format")) #("~.s" 0 3 (racket-module "racket/format")) #("blame-swapped?" 0 14 (racket-module "racket/contract")) #("struct/c" 0 8 (racket-module "racket/contract")) #("build-compound-type-name" 0 24 (racket-module "racket/contract")) #("procedure-arity-includes/c" 0 26 (racket-module "racket/contract")) #("unsupplied-arg?" 0 15 (racket-module "racket/contract")) #("list*of" 0 7 (racket-module "racket/contract")) #("struct/dc" 0 9 (racket-module "racket/contract")) #("recontract-out" 0 14 (racket-module "racket/contract")) #("flat-contract-property?" 0 23 (racket-module "racket/contract")) #("blame-add-cdr-context" 0 21 (racket-module "racket/contract")) #("continuation-mark-key/c" 0 23 (racket-module "racket/contract")) #("*list/c" 0 7 (racket-module "racket/contract")) #("any" 0 3 (racket-module "racket/contract")) #("bad-number-of-results" 0 21 (racket-module "racket/contract")) #("exn:fail:contract:blame-object" 0 30 (racket-module "racket/contract")) #("coerce-flat-contract" 0 20 (racket-module "racket/contract")) #("prop:blame" 0 10 (racket-module "racket/contract")) #("char-in" 0 7 (racket-module "racket/contract")) #("flat-murec-contract" 0 19 (racket-module "racket/contract")) #("parametric->/c" 0 14 (racket-module "racket/contract")) #("flat-named-contract" 0 19 (racket-module "racket/contract")) #("flat-rec-contract" 0 17 (racket-module "racket/contract")) #("struct:arrow-contract-info" 0 26 (racket-module "racket/contract")) #("contract-exercise" 0 17 (racket-module "racket/contract")) #("opt/c" 0 5 (racket-module "racket/contract")) #("blame-negative" 0 14 (racket-module "racket/contract")) #("define/contract" 0 15 (racket-module "racket/contract")) #("base->-rngs/c" 0 13 (racket-module "racket/contract")) #("prop:orc-contract" 0 17 (racket-module "racket/contract")) #("contract-random-generate" 0 24 (racket-module "racket/contract")) #("</c" 0 3 (racket-module "racket/contract")) #("contract-projection" 0 19 (racket-module "racket/contract")) #("blame-replaced-negative?" 0 24 (racket-module "racket/contract")) #("flat-contract?" 0 14 (racket-module "racket/contract")) ...)) (prefix predicate action) (if (eq action 'metadata) (let nil (cons 'metadata (or metadata (list (cons ... racket--identifier-category))))) (let nil (complete-with-action action completions prefix predicate)))) nil 0 (metadata (category . racket-identifier) (affixation-function . racket--xp-binding-completion-affixator)))
  completion-try-completion("\n;; It is important to run this with the correct p..." (closure ((metadata (category . racket-identifier) (affixation-function . racket--xp-binding-completion-affixator)) (completions #("in-syntax" 0 9 (racket-module "racket/sequence")) #("file->syntax" 0 12 (racket-module "syntax.rkt")) #("path->existing-syntax" 0 21 (racket-module "syntax.rkt")) #("path->existing-expanded-syntax" 0 30 (racket-module "syntax.rkt")) #("file->expanded-syntax" 0 21 (racket-module "syntax.rkt")) #("make-caching-load/use-compiled-handler" 0 38 (racket-module "syntax.rkt")) #("string->expanded-syntax" 0 23 (racket-module "syntax.rkt")) #("~s" 0 2 (racket-module "racket/format")) #("~e" 0 2 (racket-module "racket/format")) #("~v" 0 2 (racket-module "racket/format")) #("~a" 0 2 (racket-module "racket/format")) #("~r" 0 2 (racket-module "racket/format")) #("~.v" 0 3 (racket-module "racket/format")) #("~.a" 0 3 (racket-module "racket/format")) #("~.s" 0 3 (racket-module "racket/format")) #("blame-swapped?" 0 14 (racket-module "racket/contract")) #("struct/c" 0 8 (racket-module "racket/contract")) #("build-compound-type-name" 0 24 (racket-module "racket/contract")) #("procedure-arity-includes/c" 0 26 (racket-module "racket/contract")) #("unsupplied-arg?" 0 15 (racket-module "racket/contract")) #("list*of" 0 7 (racket-module "racket/contract")) #("struct/dc" 0 9 (racket-module "racket/contract")) #("recontract-out" 0 14 (racket-module "racket/contract")) #("flat-contract-property?" 0 23 (racket-module "racket/contract")) #("blame-add-cdr-context" 0 21 (racket-module "racket/contract")) #("continuation-mark-key/c" 0 23 (racket-module "racket/contract")) #("*list/c" 0 7 (racket-module "racket/contract")) #("any" 0 3 (racket-module "racket/contract")) #("bad-number-of-results" 0 21 (racket-module "racket/contract")) #("exn:fail:contract:blame-object" 0 30 (racket-module "racket/contract")) #("coerce-flat-contract" 0 20 (racket-module "racket/contract")) #("prop:blame" 0 10 (racket-module "racket/contract")) #("char-in" 0 7 (racket-module "racket/contract")) #("flat-murec-contract" 0 19 (racket-module "racket/contract")) #("parametric->/c" 0 14 (racket-module "racket/contract")) #("flat-named-contract" 0 19 (racket-module "racket/contract")) #("flat-rec-contract" 0 17 (racket-module "racket/contract")) #("struct:arrow-contract-info" 0 26 (racket-module "racket/contract")) #("contract-exercise" 0 17 (racket-module "racket/contract")) #("opt/c" 0 5 (racket-module "racket/contract")) #("blame-negative" 0 14 (racket-module "racket/contract")) #("define/contract" 0 15 (racket-module "racket/contract")) #("base->-rngs/c" 0 13 (racket-module "racket/contract")) #("prop:orc-contract" 0 17 (racket-module "racket/contract")) #("contract-random-generate" 0 24 (racket-module "racket/contract")) #("</c" 0 3 (racket-module "racket/contract")) #("contract-projection" 0 19 (racket-module "racket/contract")) #("blame-replaced-negative?" 0 24 (racket-module "racket/contract")) #("flat-contract?" 0 14 (racket-module "racket/contract")) ...)) (prefix predicate action) (if (eq action 'metadata) (let nil (cons 'metadata (or metadata (list (cons ... racket--identifier-category))))) (let nil (complete-with-action action completions prefix predicate)))) nil 0 (metadata (category . racket-identifier) (affixation-function . racket--xp-binding-completion-affixator)))
  corfu--capf-wrapper(racket-xp-complete-at-point t)
  corfu--capf-wrapper-advice(#<subr completion--capf-wrapper> racket-xp-complete-at-point all)
  apply(corfu--capf-wrapper-advice #<subr completion--capf-wrapper> (racket-xp-complete-at-point all))
  completion--capf-wrapper(racket-xp-complete-at-point all)
  completion-at-point()
  indent-for-tab-command(nil)
  funcall-interactively(indent-for-tab-command nil)
  #<subr call-interactively>(indent-for-tab-command nil nil)
  call-interactively@ido-cr+-record-current-command(#<subr call-interactively> indent-for-tab-command nil nil)
  apply(call-interactively@ido-cr+-record-current-command #<subr call-interactively> (indent-for-tab-command nil nil))
  call-interactively(indent-for-tab-command nil nil)
  command-execute(indent-for-tab-command)

Likely fix: racket--call-with-completion-prefix-positions needs to check for this condition, including avoiding a multi-line span.