Resources: Fix getting for an unknown id

[agubler]

Type: bug

The following has been addressed in the PR:

• [ ] There is a related issue
• [ ] All code has been formatted with prettier as per the readme code style guidelines
• [ ] Unit or Functional tests are included in the PR

Description:

Fixes an error that occurs if get is used for an id that doesn't exist in the resource cache.

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[codecov[bot]]

Codecov Report

Merging #884 (80a3392) into master (c3b4866) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #884   +/-   ##
=======================================
  Coverage   94.52%   94.52%           
=======================================
  Files         127      127           
  Lines        8094     8095    +1     
  Branches     1888     1889    +1     
=======================================
+ Hits         7651     7652    +1     
  Misses        443      443           

Impacted Files	Coverage Δ
src/core/middleware/resources.ts	95.69% <100.00%> (+0.01%)	:arrow_up:

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