panflute.yaml_filter: error handling when YAML is invalid about panflute HOT 4 CLOSED

I agree that Python errors should not be allowed to occur.

We could just wrap the YAML reader in a try ... except code, and if it fails, then do nothing but issue a warning message?

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In addition to a warning message in command-line, how about it returns the options with only 1 key, say, {'yaml-error': True}, so that individual filters can decide how to deal with it? (e.g. One can continue to work with the data while ignoring the options with "sensible defaults".)

By the way, I tested invalid YAML in pandoc and it will do:

$ printf "%s\n" '---' 'title: *unquoted*' '---' '' 'non-empty' | pandoc -f markdown -t native --css=abc.css
pandoc: Could not parse YAML header: did not find expected alphabetic or numeric character "source" (line 3, column 17)
Pandoc (Meta {unMeta = fromList []})
[Para [Str "non-empty"]]

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I wrote the code for the soft error handling, but I think that at least for now the better alternative is not to run the filter at all:

• It would allow the reader of the output to inspect what went wrong (you can just read the code block)
• The errors would be harder to spot (e.g. a table might have the wrong title, instead of just appearing as a code block)
• It would add even more complexity to the YAML filter

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I finished my filter in ickc/pantable: CSV Tables in Markdown: Pandoc Filter for CSV Tables. It's based on your csv example but eventually breaks compatibility with it.

One potential problem is exactly what you said above: I handle away all errors in the YAML metadata and override them with "sensible defaults".

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