fix: only call error handler if status code is >= 400

[danielroe]

resolves #150

[codecov]

Codecov Report

Merging #153 (e57922e) into main (63232f5) will decrease coverage by 0.22%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##             main     #153      +/-   ##
==========================================
- Coverage   85.89%   85.66%   -0.23%     
==========================================
  Files           5        5              
  Lines         319      321       +2     
  Branches       60       60              
==========================================
+ Hits          274      275       +1     
- Misses         45       46       +1     

Impacted Files	Coverage Δ
src/fetch.ts	86.48% <85.71%> (-0.40%)	⬇️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.