catch errors and log a stack trace

[naturallymitchell]

currently, we have try-catch. https://github.com/foundpatterns/torchbear/blob/2b7737008f925b793dff466dbdd508ece9baacf5/src/managers/web_server.lua#L8-L21

if we https://github.com/kyren/rlua/issues/88 , we can get a stack trace.

error message can go in log.error().

[naturallymitchell]

@Arnaz87 anything left here?

[Arnaz87]

fixed at some point, by using xpcall in here and here

[naturallymitchell]

:+1: