fix: js exception when reloading async chunk (#444)

[Rulexec]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

HMR throws exception every time when I do edits in my css files:

Uncaught TypeError: Cannot read property 'some' of null
    at getReloadUrl (hotModuleReplacement.js:129)
    at hotModuleReplacement.js:145
    at NodeList.forEach (<anonymous>)
    at reloadStyle (hotModuleReplacement.js:140)
    at update (hotModuleReplacement.js:194)
    at functionCall (hotModuleReplacement.js:24)

This fix ignores such obviously wrong updates and allows to use options.reloadAll, because this exception happens just before reloadAll() call.

Issue — #444

Breaking Changes

None.

[jsf-clabot]

All committers have signed the CLA.

[alexander-akait]

Please add a test

[alexander-akait]

Or please create reproducible test repo

[Rulexec]

Reproducible test branch.

I will try to write test, but it can take a while to investigate, how to write such test.

[codecov]

Codecov Report

Merging #531 into master will increase coverage by 0.33%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #531      +/-   ##
==========================================
+ Coverage   88.49%   88.83%   +0.33%     
==========================================
  Files           5        5              
  Lines         426      430       +4     
  Branches       94       95       +1     
==========================================
+ Hits          377      382       +5     
+ Misses         47       46       -1     
  Partials        2        2              

Impacted Files	Coverage Δ
src/hmr/hotModuleReplacement.js	89.28% <100.00%> (+1.32%)	⬆️

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[alexander-akait]

We should use mock for test it, no need it in runtime code

[Rulexec]

How to mock variable inside module?

Currently value inside srcByModuleId persists between tests and my situation happens only if it's clear.