Better Liquid tag error handling

[maestromac]

Is your feature request related to a problem? Please describe.
Whenever there's an error in the liquid tag, the editor should try it's best to inform the author what went wrong and not display the dreaded Liquid error: internal. This has also proven to be difficult to debug in development.

Describe the solution you'd like
Currently, we are making our individual custom liquid tag to raise StandardError upon initialization if there's an... ArgumentError. We are doing this because any form of error that happens within #render will throw a Liquid error: internal.

A better solution would be to let Liquid parse normally, ie Liquid::Template.parse(sanitized_content), then check for errors with Liquid.errors. This also has the added benefit of catching multiple errors at once, letting them be added to errors to be displayed in the view.

Describe alternatives you've considered
There could be a better solution I've missed in this documentation.

Additional context
This should also account both of our editor versions.

[rhymes]

This contains useful information as well #7898

[marcospedro97]

This issue is available? Can I give it a try?

[maestromac]

Yes @marcospedro97 . Please give it a try!

[marcospedro97]

While working in the issue I've manged to catch more errors than we have currently, the main problem I've seen on issue #7898 is that even with the problem the post was created, using the parsed_liquid.errors in the markdown parser this wouldn't happen again, but this didn't allow me to show more than a single error in the view (at least without changing the view code, or maybe the code of the liquid, I didn't check who's the one that give this behavior), I've also started asking myself if giving the line were the error occurred wouldn't be a improvement since debugging that post was clearly a problem, if anyone has a thought to share about this, I would be glad to read