range of behaviors when adding char after expanded kw eg. "let| x = 5 in"

[disconcision]

so the simple case is fine. inserting another "t" above just results in "lett" and no ghosts.

but given this:

entering another "t" crashes:

and given:

inserting "t" results in:

[dm0n3y]

above commit fixes crash but not the lettin issue