Fix svg parsing in case it uses empty use tag or use with image href

[andrejslogins]

Fix cases where parsing string to svg was crashing.

Added the two test cases where this occurs.
1st case (empty ) occurs because xLinkAttribute is null (line 476)
2nd case (image href) occurs because element.parentNode is null

Didn't bump dist files as i'm not aware if this should be done in scope of PRs or not

[asturur]

what is this function returning on the others return early case? are we safe returning undefined?

[andrejslogins]

no explicit returns are there in the following code, so it's safe

edit for clarity:

There are no other return statements in parseUseDirectives

[andrejslogins]

Only usage here (src/parser.js):

 fabric.parseSVGDocument = function(doc, callback, reviver, parsingOptions) {
    if (!doc) {
      return;
    }

    parseUseDirectives(doc);
    ..........
    ..........
    ..........

[andrejslogins]

For checks:

• Pr quality check / coverage (pull_request) :Error: Resource not accessible by integration , looks like this is unrelated to the PR itself

[andrejslogins]

@asturur All good from your side?

[asturur]

Sorry i have been away

[asturur]

So to clarify my question, the first time i looked at the PR i must have opened to much diff lines or to few, and i was seeing some other returns, but i see i was watching something else.

Pr looks good, i m merging it. Next time try to avoid unnecessary format changes, however they may look better, they create non necessary diff changes to look at.

Unless is a specific linting PR.

[andrejslogins]

sure, will keep in mind. thanks