Use Flask error handlers instead of decorators (#74)

[nickeopti]

Closes #74

[codecov]

Codecov Report

Merging #227 (2b90eeb) into main (c1c5b56) will decrease coverage by 0.00%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##             main     #227      +/-   ##
==========================================
- Coverage   98.46%   98.46%   -0.01%     
==========================================
  Files          45       45              
  Lines        2221     2211      -10     
  Branches      278      276       -2     
==========================================
- Hits         2187     2177      -10     
  Misses         19       19              
  Partials       15       15              

Impacted Files	Coverage Δ
terracotta/server/flask_api.py	90.27% <80.95%> (ø)
terracotta/server/colormap.py	97.22% <100.00%> (-0.08%)	⬇️
terracotta/server/compute.py	100.00% <100.00%> (ø)
terracotta/server/datasets.py	100.00% <100.00%> (ø)
terracotta/server/keys.py	100.00% <100.00%> (ø)
terracotta/server/metadata.py	100.00% <100.00%> (ø)
terracotta/server/rgb.py	96.07% <100.00%> (-0.15%)	⬇️
terracotta/server/singleband.py	100.00% <100.00%> (ø)

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[j08lue]

This nicely tidies up the code base. Looks good to me! I am pretty sure we cover all the exceptions (and their expected error codes) in the tests, so this seems to work as expected.

@dionhaefner, do you want to take a brief look at it to verify that this is what you had in mind?

[dionhaefner]

LGTM 👍