Don't put stack trace in the exception message

[zbstof]

Exception stacktrace for each error could be easily extracted by doing
((FatalTemplateErrorsException) e).getErrors().get(n).getException(),
if needed

[zbstof]

Problem for us was that we tried extract root cause's message ourselves, and this works ok except with this library, which caused buffer overflow down the line.

[boulter]

Thanks, @zbstof!