Add better handling of errors on request

[thomasrockhu]

Fix for https://community.codecov.io/t/cannot-upload-to-codecov-after-upgrade-to-0-2-8-codecov-ruby-gem/1912/6

[codecov]

Codecov Report

Merging #99 into master will decrease coverage by 0.26%.
The diff coverage is 60.00%.

@@            Coverage Diff             @@
##           master      #99      +/-   ##
==========================================
- Coverage   92.06%   91.80%   -0.27%     
==========================================
  Files           1        1              
  Lines         353      354       +1     
==========================================
  Hits          325      325              
- Misses         28       29       +1     

Impacted Files	Coverage Δ
lib/codecov.rb	91.80% <60.00%> (-0.27%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bba4658...53239ad. Read the comment docs.