Add a method to retry resolution and pass it to error component

[nathanstitt]

I use react-async-component for loading web pack modules with import() and find that they sometimes will timeout or otherwise fail to load.

I'd like to add a button to my ErrorComponent but there wasn't a way to do so. This provides a function that could be called.

I've tested with simulated network timeout by putting Chrome offline and seems to work well.

I also added a spec and noticed a few things that could be improved there. Happy to rework if you spot anything else.

[codecov]

Codecov Report

Merging #70 into master will increase coverage by 2.42%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master     #70      +/-   ##
=========================================
+ Coverage   94.38%   96.8%   +2.42%     
=========================================
  Files           3       3              
  Lines          89      94       +5     
  Branches       25      25              
=========================================
+ Hits           84      91       +7     
+ Misses          5       3       -2

Impacted Files	Coverage Δ
src/asyncComponent.js	96.05% <100%> (+3.09%)	⬆️

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[hochem]

Any updates on this PR? I have the same problem (failed components will never resolve once networking is up again) and I would like to have this feature in the lib.

[mgreer]

I implement this as an HOC wrapper around async, to retry with backoff:
https://gist.github.com/mgreer/eb33c95d22cabcec22a26b28acacaa16
Happy to contribute this as an option in the lib too.