System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, EventbriteSync.EventbriteOpportunityTrigger: execution of AfterInsert
caused by: System.NullPointerException: Attempt to de-reference a null object
Trigger.EventbriteSync.EventbriteOpportunityTrigger: line 4, column 1: []

System.UnexpectedException: No more than one executeBatch can be called from within a test method. Please make sure the iterable returned from your start method matches the batch size, resulting in one executeBatch invocation.  Stack Trace: External entry point