Fix: Empty string as template in CustomPlot.init

[anunayasri]

Fixes #10482 (report in dvc repo) at iterative/dvc#10482

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[dberenbaum]

Thanks @anunayasri! As long as we are fixing it for the empty string, can we also handle any string that's not a supported template?

[shcheklein]

Thanks @anunayasri! As long as we are fixing it for the empty string, can we also handle any string that's not a supported template?

@dberenbaum how do we recognize that? run Vega parser / validator?

[skshetry]

I think we should just disallow empty string.

[skshetry]

In any case, this template.strip() is unnecessary.

Suggested change

	if template is not None and template.strip() == "":
	template = None
	if not template:
	template = None

[anunayasri]

@skshetry Thanks. This is much cleaner.

[anunayasri]

There is a missing None check in my commit and mypy failing the pipeline. I have correct it.
I observed that $ pre-commit run --all-files does not run mypy in the local. Is it by design? May be to speed up the pre-commit exeuction.

[skshetry]

I don't think it's worth it to add this test, has very less return.

We can't test for every combinations.

[anunayasri]

Since template = '' caused a cryptic error, I added this test as a guardrail to ensure that any template = None is handled explicitly.
But on a second thought, I think you are correct. This test is for log_plot() which has default value for template. CustomPlot.__init__() doesn't have a default value for template but that shouldn't be test here.
Will rectify.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.18%. Comparing base (602c053) to head (bf8ff74).
Report is 32 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #841      +/-   ##
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- Coverage   95.47%   95.18%   -0.29%     
==========================================
  Files          57       55       -2     
  Lines        3889     3904      +15     
  Branches      353      349       -4     
==========================================
+ Hits         3713     3716       +3     
- Misses        124      138      +14     
+ Partials       52       50       -2     

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[dberenbaum]

@dberenbaum how do we recognize that? run Vega parser / validator?

🤔 I forgot we don't render these anywhere here, and supporting custom templates would not be easy, so forget my initial suggestion.