Display error message for NetworkErrorCode

[congwang]

This is to resolve #1654.

[billonahill]

Can these instead be bound directly to the enum values themselves, instead of managed separately?
http://en.cppreference.com/w/cpp/language/enum

[congwang]

I am not aware of any C++ syntax for this, we may achieve it by a wrapper class or something like that, but I doubt it is worth the effort to improve it. Does it hurt readability to you?

[objmagic]

this looks useful https://aantron.github.io/better-enums/tutorial/Conversions.html#Strings and easy to include in, if we bother to use it at all...

[congwang]

There is always some way to do it. Again, why do you think it is worth our effort to do it? For me, we only have one case so far, no need to bother a complex way to make it unnecessarily elegant. If you believe it is worth, you are welcome to do it in a separate PR.

[objmagic]

just pointing out. i have no opinion since C++ language does not have the capability of allowing people to use enum reflection easily.

[objmagic]

can you check out the CI?

[congwang]

@objmagic IntegrationTest_MultiSpoutsMultiTasks fails.

[congwang]

There is a new CI failure:

[ RUN      ] StMgr.test_tmaster_restart_on_new_address
src/central_freelist.cc:333] tcmalloc: allocation failed 24576 
Unknown exception caught in global handler

[objmagic]

Thanks. I'll just restart the CI.

[objmagic]

The PR CI is fine. Feel free to merge it.

[objmagic]

The PR CI check passed. Merged.