fix: onerror mem leak

[dgeibi]

This PR contains a:

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

Motivation / Use-Case

Fixes #639

Breaking Changes

No

Additional Info

No

[jsf-clabot]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #640 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #640   +/-   ##
=======================================
  Coverage   89.55%   89.55%           
=======================================
  Files          11       11           
  Lines         651      651           
  Branches      181      181           
=======================================
  Hits          583      583           
  Misses         65       65           
  Partials        3        3           

Impacted Files	Coverage Δ
src/CssLoadingRuntimeModule.js	97.05% <ø> (ø)
src/index.js	91.35% <ø> (ø)

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[alexander-akait]

Example of fix https://github.com/webpack/webpack/blob/db36afea4dfe0b76e66c04cd9429194c3b140002/lib/runtime/LoadScriptRuntimeModule.js#L125

[dgeibi]

@evilebottnawi Do you mean I should add this line "prev(event)" ?

[alexander-akait]

We should move onerror handler to separate function and handle this (look at link), we should generate runtime as little as possible

[dgeibi]

Is the generated code ok like this?

var onStyleComplete = function (event) {
  // avoid mem leaks
  linkTag.onerror = linkTag.onload = null;
  if (event.type === 'load') {
    resolve();
  } else {
    var request = (event && event.target && event.target.href) || fullhref;
    var err = new Error(
      'Loading CSS chunk ' + chunkId + ' failed.\n(' + request + ')'
    );
    err.code = 'CSS_CHUNK_LOAD_FAILED';
    err.request = request;
    linkTag.parentNode.removeChild(linkTag);
    reject(err);
  }
};
linkTag.onerror = linkTag.onload = onStyleComplete;

[alexander-akait]

Yes 👍

[alexander-akait]

Good job, thanks