mail keeps crashing please advise
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY
Application Specific Information:
*** Terminating app due to exception while holding database lock 'NSInvalidArgumentException', reason: '*** -[__NSSetM addObject:]: object cannot be nil', userInfo: (null)
abort() called
MacBook Pro 13", macOS 10.13