handle undefined trash in case of an error

[sarahd93]

In case of an error on the trashcanpage the trash might be undefined which would cause the trashcanpage to break. This PR should fix that by catching this special case.

Checklist:

• [N/A] Tests
• CHANGELOG Entry

[codecov]

Codecov Report

Merging #1908 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1908      +/-   ##
==========================================
- Coverage   49.22%   49.22%   -0.01%     
==========================================
  Files        1043     1043              
  Lines       24671    24674       +3     
  Branches     6999     6974      -25     
==========================================
  Hits        12145    12145              
- Misses      11377    11379       +2     
- Partials     1149     1150       +1

Impacted Files	Coverage Δ
gsa/src/web/pages/extras/trashcanpage.js	3.27% <0%> (-0.06%)	⬇️

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