[PR] Returning JSON in ErrorView when appropriate headers are passed

[LuchoTurtle]

closes #269

Will return a JSON response, even if Content-type is the only request header specified (Phoenix differentiates using the Accept header).

It also resolves a warning of a variable that was unused and removes app/datetime_parser.ex, which is unused and was introduced in a recent commit.

[codecov[bot]]

Codecov Report

Merging #270 (01e1ed2) into main (dcaaf18) will increase coverage by 9.34%. The diff coverage is 100.00%.

@@             Coverage Diff             @@
##             main      #270      +/-   ##
===========================================
+ Coverage   90.65%   100.00%   +9.34%     
===========================================
  Files          15        14       -1     
  Lines         428       400      -28     
===========================================
+ Hits          388       400      +12     
+ Misses         40         0      -40     

Impacted Files	Coverage Δ
lib/app_web/views/error_view.ex	100.00% <100.00%> (ø)
lib/app_web/live/app_live.ex	100.00% <0.00%> (+0.83%)	:arrow_up:

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[LuchoTurtle]

This PR should be complete and ready for review. 👍