Add basic exception handling

[RayceRossum]

• This allowed for the removal of testing if the file exists as imread will throw a FileNotFoundError itself.

[codecov-io]

Codecov Report

Merging #37 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #37   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           4      4           
  Lines          67     90   +23     
=====================================
+ Hits           67     90   +23

Impacted Files	Coverage Δ
AutoTransformPy/translate.py	100% <100%> (ø)	⬆️
AutoTransformPy/rotate.py	100% <100%> (ø)	⬆️
AutoTransformPy/mirror.py	100% <100%> (ø)	⬆️

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