JS compiler fixes after new compiler release

[bryk]

This change is

[bryk]

@floreks Can you take a look?

[codecov-io]

Current coverage is 86.89%

Merging #581 into master will increase coverage by +0.35% as of 185a7d0

@@            master    #581   diff @@
======================================
  Files           97     102     +5
  Stmts          847     870    +23
  Branches         0       0       
  Methods          0       0       
======================================
+ Hit            733     756    +23
  Partial          0       0       
  Missed         114     114       

Review entire Coverage Diff as of 185a7d0

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[floreks]

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Reviewed 6 of 6 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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Comments from the review on Reviewable.io