Errors

A good error message should make it self-evident

• what the user did
• what the acceptable inputs are
• how to fix the problem

ConfigError: can't find 'ffprobe' to extract video metadata; have you run `brew install ffmpeg`

...rather than...

FileNotFoundError: [Errno 2] No such file or directory

References

• Error-Message Guidelines, Tim Neusesser and Evan Sunwall
• Exceptionally Tricky: Good errors in bad situations, Alistari Lynn