fix: handle missing tree-sitter-language binaries

[tconbeer]

Please review the following checklist.

• Docstrings on all new or modified functions / classes
• Updated documentation
• Updated CHANGELOG.md (where appropriate)

Closes #4045

I don't think new documentation is necessary. Happy to provide if you disagree.

[davep]

I've not looked to see if it is affected or not, but note that #3933 is close to being merged and has a lot of changes to all things TextArea; so keep in mind that this might get held back for a wee while until that's merged, or perhaps run this by @darrenburns as a small addition there (there is also a followup PR to come that will make some other QoL changes to TextArea, so it might make sense that it rolls into that).

[tconbeer]

Thanks, Dave. I'm fine if this waits on the other PR, although a quick scan through the changes didn't reveal any obvious conflicts

[darrenburns]

Strange - this doesn't happen for me if I uninstall tree-sitter-languages. The functionality is supposed to degrade with a logged warning in the console:

The intention is that the constructor of SyntaxAwareDocument shouldn't even be called if tree-sitter-languages is unavailable (I would expect TREE_SITTER to be False on the line shown below, which results in a plain Document being created).

textual/src/textual/widgets/_text_area.py

Line 625 in 23735cd

if TREE_SITTER and language:

textual/src/textual/_tree_sitter.py

Line 10 in bbde62f

TREE_SITTER = False

So it seems the binaries can be installed and then fail in some environments?

I don't understand the root cause, but I think handling this error is still a good call regardless.

[darrenburns]

Ah, I think I understand now. So the tree-sitter-languages package on Conda is broken such that the package is available, but doesn't actually contain the required binaries... I think? So, installation of tree-sitter-languages succeeds, but it's essentially an empty package 😄

[willmcgugan]

Thanks @tconbeer !