throw exception('HiveException') needs be same as throw HiveException()
throw exception('HiveException') needs be same as throw HiveException()

Bug: If an exception of a particular type is missing in EXCEPTION_CLASS, it will fall back to EXCEPTION_BASE even if that exception's class exists
eg.
In case of 'HiveException', throw exception('HiveException') was throwing EnsEMBL::Web::Exception even when EnsEMBL::Web::Exception::HiveException existed
throw HiveException(), however was throwing EnsEMBL::Web::Exception::HiveException as expected

Fix:
Do the same check to find the exception class in both places - when calling import() and exception()

Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-webcode