[READY] Support TypeScript 2.6.1

[micbou]

TypeScript 2.6.1 introduced a bug in TSServer where NPM warnings are printed on stdout at startup:

npm WARN 2.6 No description
npm WARN 2.6 No repository field.
npm WARN 2.6 No license field.

See issue microsoft/TypeScript#19660. The TypeScript completer chokes on this output as it always expects a HTTP-like response from TSServer and assumes that the server died if not. Though it's a TSServer bug, we can handle it by catching the ValueError exception raised when parsing invalid headers and by interrupting the reader loop only if the server is not running.

Also, this new version of TypeScript returns an empty list when no definition is found. Update the _GoToDefinition and _GoToType functions accordingly.

Fixes ycm-core/YouCompleteMe#2818.

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This change is 

[puremourning]

TBH i'd rather just restrict the version of tsserver that we use and point people having the issue at the bug, but we would at least have to fix the other part (about goto).

Are we certain that the npm messages will only appear during header parsing ? The code for parsing message body isn't very robust either, but is it possible for the npm message to appear after a valid content-length: ...\n\n but before an actual message ?

I would be surprised if it is, or if we should even worry about it, but thought i'd ask anyway.

assuming that and that the tests finally pass :)

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Reviewed 2 of 2 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from Reviewable

[codecov-io]

Codecov Report

Merging #869 into master will decrease coverage by 0.06%.
The diff coverage is 87.5%.

@@            Coverage Diff            @@
##           master    #869      +/-   ##
=========================================
- Coverage   94.77%   94.7%   -0.07%     
=========================================
  Files          79      79              
  Lines        5435    5440       +5     
  Branches      171     171              
=========================================
+ Hits         5151    5152       +1     
- Misses        235     239       +4     
  Partials       49      49

[bstaletic]

Are we certain that the npm messages will only appear during header parsing ?

This is my concern too. If we can't be certain we better restrict tsserver version.
But if we can be certain, this is

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Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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Comments from Reviewable

[micbou]

is it possible for the npm message to appear after a valid content-length: ...\n\n but before an actual message ?

Looking at TSServer code, the whole response is written at once on stdout (see formatMessage) so it shouldn't be possible.

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Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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Comments from Reviewable

[puremourning]

Shall we ship it then? Fire when ready!

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Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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Comments from Reviewable

[micbou]

@zzbot r+

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Reviewed 2 of 2 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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Comments from Reviewable

[zzbot]

📌 Commit 5f98ed4 has been approved by micbou

[zzbot]

⌛ Testing commit 5f98ed4 with merge 0c2a614...

[zzbot]

☀️ Test successful - status-appveyor, status-travis
Approved by: micbou
Pushing 0c2a614 to master...