If GroovyEngine.serviceInvoker catches an exception in a Groovy script, it would mask the exception in some cases. An exception's detailMessage can be null. If it is null, the exception won't be properly returned and logged, and that will make spotting problems very difficult. This was the case for me while trying to track down a problem with a java.util.ConcurrentModificationException error in a Groovy script. I suspect that this choice to mask exceptions and only return the message has cause bugs to not be spotted.
Disabling this for now in favor of returning a proper exception. GroovyEngine.serviceInvoker() should throw GenericServiceException if error, rather than returning ServiceUtil.returnError(e.getMessage())