catch unhandled rejection with installation-handling

[kahoona77]

Hi,

as mentioned in #3758 I now found the time to fix the unhandled rejections when dealing with installations. I added catch-blocks to the delete-statements in RestWrite.js . The error is ignored when it is "ObjectNotFound". Otherwise it will be rethrown.
We already use this in our production environment without problems. And log log now no longer has "unhandled rejection" warnings.

Best regards,
Benjamin

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@8d67776). Click here to learn what that means.
The diff coverage is 27.27%.

@@           Coverage Diff            @@
##             master   #3795   +/-   ##
========================================
  Coverage          ?   90.1%           
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  Files             ?     114           
  Lines             ?    7500           
  Branches          ?       0           
========================================
  Hits              ?    6758           
  Misses            ?     742           
  Partials          ?       0

Impacted Files	Coverage Δ
src/RestWrite.js	93.21% <27.27%> (ø)

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[flovilmart]

Fixes #3758