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videolang / video

Source Code for Video language.
https://lang.video
Apache License 2.0
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Unfortunate error messsage #12

Closed BenChung closed 6 years ago

BenChung commented 7 years ago

When a make-producer is given a #:source argument of a playlist, the following error is produced:

string->bytes/utf-8: contract violation
  expected: string?
  given: (playlist '#hash() #<procedure:temp419> '() #f #f #f #f #f #f #f (list (producer '#hash(                                                                                                                                                                                                                                                                          ) #<procedure:temp269> '() #f "/home/benchung/Work/pliss/racket_video/../PLISS_Jun18_11-45-11.mov                                                                                                                                                                                                                                                                          " #f #f #f #f #f) (producer '#hash() #<procedure:temp269> '() #f "/h...
  context...:
   /home/benchung/Work/pliss/racket_video/video-local/video/video/private/mlt.rkt:236:34
   /home/benchung/Work/pliss/racket_video/video-local/video/video/private/video.rkt:180:29
   /usr/share/racket/collects/racket/private/more-scheme.rkt:373:13: hash-ref!
   /home/benchung/Work/pliss/racket_video/video-local/video/video/render.rkt:125:4: prepare metho                                                                                                                                                                                                                                                                          d in render%
   /home/benchung/Work/pliss/racket_video/video-local/video/video/private/video.rkt:294:2: for-lo                                                                                                                                                                                                                                                                          op
   /home/benchung/Work/pliss/racket_video/video-local/video/video/private/video.rkt:180:29
   /usr/share/racket/collects/racket/private/more-scheme.rkt:373:13: hash-ref!
   /home/benchung/Work/pliss/racket_video/video-local/video/video/render.rkt:125:4: prepare metho                                                                                                                                                                                                                                                                          d in render%
   /home/benchung/Work/pliss/racket_video/video-local/video/video/private/video.rkt:265:2: for-lo                                                                                                                                                                                                                                                                          op
   /home/benchung/Work/pliss/racket_video/video-local/video/video/private/video.rkt:180:29
   /usr/share/racket/collects/racket/private/more-scheme.rkt:373:13: hash-ref!
   /home/benchung/Work/pliss/racket_video/video-local/video/video/render.rkt:125:4: prepare metho                                                                                                                                                                                                                                                                          d in render%
   /home/benchung/Work/pliss/racket_video/video-local/video/video/render.rkt:62:0: render27
   /usr/share/racket/collects/racket/contract/private/arrow-val-first.rkt:397:3

This error, while expected (as source is expected to be a path, not a producer), is not very clear as to why and where the issue occurred. Rather, the #:source parameter should have a contract that guarantees that the passed argument is a string (and preferably also checks validity, too), making the root cause clearer to the user.

LeifAndersen commented 6 years ago

While I'm sure that Video needs much cleaner error messages. This particular error message is now no longer visible in v0.2. Please open new issues like it though. :)