JavaScript: avoid assertion failures when making an empty tag

[masatake]

Related to #900, #1112, and #3427.

When the parser tries making a tag with empty name, an assertion
in registerEntry fails. The parser side should be fixed but it
will take a time. This change puts guard conditions around
registerEntry to avoid the failures.

THIS IS A TEMPORARILY SOLUTION.

Signed-off-by: Masatake YAMATO yamato@redhat.com

[codecov]

Codecov Report

Merging #3428 (cf68aae) into master (b6ac374) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #3428   +/-   ##
=======================================
  Coverage   83.35%   83.35%           
=======================================
  Files         218      218           
  Lines       52487    52488    +1     
=======================================
+ Hits        43749    43750    +1     
  Misses       8738     8738           

Impacted Files	Coverage Δ
parsers/jscript.c	97.58% <100.00%> (+<0.01%)	⬆️

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[jafl]

I was just going to submit a PR for this :)

[masatake]

Testing on BSDs becomes a bottleneck of development.

[masatake]

I was just going to submit a PR for this :)

I recognized the assertion failures with codebase.
https://docs.ctags.io/en/latest/contributions.html#add-realistic-examples-for-you-parser-to-codebase

You know JavaScript well. So you can run semi-test JavaScript in your brain.
However, I am not. This is not only JavaScript but all other languages than C.
So I have gathered REAL source code for various languages for testing parsers of ctags.

See https://github.com/universal-ctags/codebase. I think this is useful for a developer even if the one knows well about the target language.