Improve error handling

[bradjones1]

Fixes #306

[codecov[bot]]

Codecov Report

Patch coverage: 66.66% and project coverage change: -0.96 :warning:

Comparison is base (0348af2) 99.27% compared to head (906985a) 98.32%.

:exclamation: Current head 906985a differs from pull request most recent head 6e31baf. Consider uploading reports for the commit 6e31baf to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #307      +/-   ##
==========================================
- Coverage   99.27%   98.32%   -0.96%     
==========================================
  Files          11       11              
  Lines         416      418       +2     
  Branches       64       70       +6     
==========================================
- Hits          413      411       -2     
  Misses          3        3              
- Partials        0        4       +4     

Impacted Files	Coverage Δ
src/transports/EventEmitterTransport.ts	96.66% <66.66%> (-3.34%)	:arrow_down:
src/transports/HTTPTransport.ts	97.72% <66.66%> (-2.28%)	:arrow_down:
src/transports/TransportRequestManager.ts	97.84% <66.66%> (-1.06%)	:arrow_down:
src/transports/WebSocketTransport.ts	97.14% <66.66%> (-2.86%)	:arrow_down:

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[bradjones1]

Surprisingly, this doesn't break any tests! Probably means we need to add testing for this :-)