[TINKERPOP-3112] Javascript: fix memory leak on server error

[ohana54]

Jira link: https://issues.apache.org/jira/browse/TINKERPOP-3112

This PR fixes a memory leak in the case the server responds with an error.
I observed the leak in our environment, took heap snapshots and traced it down to not removing response handlers in case of a server error.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.41%. Comparing base (d9e34fb) to head (890f761).
Report is 121 commits behind head on 3.6-dev.

Additional details and impacted files

@@              Coverage Diff              @@
##             3.6-dev    #2807      +/-   ##
=============================================
+ Coverage      75.14%   75.41%   +0.26%     
- Complexity     12346    12365      +19     
=============================================
  Files           1058     1033      -25     
  Lines          63610    59901    -3709     
  Branches        6962     6974      +12     
=============================================
- Hits           47801    45173    -2628     
+ Misses         13225    12332     -893     
+ Partials        2584     2396     -188     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[kenhuuu]

Thank you for contributing. Even though this change is small, it would still be best to add an entry to the CHANGELOG.

VOTE+1, pending CHANGELOG entry.

[Cole-Greer]

Thanks for the contribution.

VOTE +1

Just an FYI, our voting process requires 3 votes to merge, or 1 week to pass after a single vote. A committer will merge your PR once it has sufficient votes.