Error from NonTrivialCongruenceClasses not caught

[reiniscirpons]

Currently when trying to call

gap> NonTrivialCongruenceClasses(CongruencesOfSemigroup(FreeBand(2))[1]);

GAP throws an exception and then terminates

terminate called after throwing an instance of 'libsemigroups::LibsemigroupsException'
  what():  src/cong-intf.cpp:310:non_trivial_classes_impl: Cannot determine the parent FroidurePin and so cannot compute non-trivial classes!
Aborted (core dumped)

It would be better if this exception was caught and did not lead to termination.

[james-d-mitchell]

Resolved in v3.3.2