lib client-api/src/client_api: check type of module.id as fileName

[ehzhang]

Issue: #5907

What I did

Much further downwind when searching through file names, fuzzy-search
and .includes requires that parameters.fileName is a string, and can't handle a
number. This checks to make sure that the fileName is indeed a string,
since webpack may sometimes return the module.id as a number.

https://webpack.js.org/api/module-variables/#moduleid-commonjs

How to test

• Force a webpack config to mode = "production"
• Start typing multiple letters
• See that the search works

[shilman]

Great bug and thanks for the fix!! @ndelangen @tmeasday seems reasonable?

[ehzhang]

@shilman i re-pushed to this branch after your approval since i noticed some failing test cases in client_api.test.js, if you'd like to take another pass.

the MockModule in the hot module loading test cases doesn't have an id defined, so it seemed the expected behavior was actually to return undefined.

I changed the little ternary above to return undefined instead of null, and added a test case to make sure we ignore the id if it isn't available from the module

An alternative would be to add fileName: null to the expect calls in the hot module functions, but wasn't sure about y'alls preferences wrt null vs undefined here (I tend to prefer undefined)

[codecov]

Codecov Report

Merging #5909 into next will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##             next    #5909   +/-   ##
=======================================
  Coverage   34.97%   34.97%           
=======================================
  Files         648      648           
  Lines        9480     9480           
  Branches     1333     1360   +27     
=======================================
  Hits         3316     3316           
  Misses       5534     5534           
  Partials      630      630

Impacted Files	Coverage Δ
lib/client-api/src/client_api.js	79.41% <100%> (ø)	⬆️

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