Server API stores storage thread callback to bucket post deletion resulting in a crash if called

172.23.122.111 : Stack Trace of first crash: 18b10b7c-1983-4573-0b8ab49d-804306f3.dmp

Core was generated by `/opt/couchbase/bin/memcached -C /opt/couchbase/var/lib/couchbase/config/memcach'.

 #0  0x00007f74d7dc9d20 in MagmaKVStoreConfig::setStorageThreads(unsigned long) () from /opt/couchbase/bin/../lib/libep.so

 #0  0x00007f74d7dc9d20 in MagmaKVStoreConfig::setStorageThreads(unsigned long) () from /opt/couchbase/bin/../lib/libep.so

 #1  0x0000000000444723 in CreateBucketThread::create() ()

 #2  0x0000000000444c79 in CreateBucketThread::run() ()

 #3  0x00007f74d66445df in Couchbase::Thread::thread_entry() () from /opt/couchbase/bin/../lib/libplatform_so.so.0.1.0

 #4  0x00007f74d6639947 in platform_thread_wrap(void*) () from /opt/couchbase/bin/../lib/libplatform_so.so.0.1.0

 #5  0x00007f74d3e7ee65 in start_thread () from /lib64/libpthread.so.0

 #6  0x00007f74d3ba788d in clone () from /lib64/libc.so.6

172.23.122.111 : Looking for CRITICAL messages in log

172.23.122.111 : Found message in /opt/couchbase/var/lib/couchbase/logs/memcached.log.000002.txt

2020-09-23T16:58:46.487095-07:00 CRITICAL Breakpad caught a crash (Couchbase version 7.0.0-3193). Writing crash dump to /opt/couchbase/var/lib/couchbase/crash/18b10b7c-1983-4573-0b8ab49d-804306f3.dmp before terminating.

2020-09-23T16:58:46.487106-07:00 CRITICAL Stack backtrace of crashed thread:

2020-09-23T16:58:46.487327-07:00 CRITICAL     /opt/couchbase/bin/memcached() [0x400000+0x19428d]

2020-09-23T16:58:46.487343-07:00 CRITICAL     /opt/couchbase/bin/memcached(_ZN15google_breakpad16ExceptionHandler12GenerateDumpEPNS0_12CrashContextE+0x3ea) [0x400000+0x1aa60a]

2020-09-23T16:58:46.487355-07:00 CRITICAL     /opt/couchbase/bin/memcached(_ZN15google_breakpad16ExceptionHandler13SignalHandlerEiP9siginfo_tPv+0xb8) [0x400000+0x1aa948]

2020-09-23T16:58:46.487364-07:00 CRITICAL     /lib64/libpthread.so.0() [0x7f74d3e77000+0xf5f0]

2020-09-23T16:58:46.487375-07:00 CRITICAL     /opt/couchbase/bin/../lib/libep.so() [0x7f74d7b5f000+0x26ad20]

2020-09-23T16:58:46.487386-07:00 CRITICAL     /opt/couchbase/bin/memcached() [0x400000+0x44723]

2020-09-23T16:58:46.487395-07:00 CRITICAL     /opt/couchbase/bin/memcached() [0x400000+0x44c79]

2020-09-23T16:58:46.487404-07:00 CRITICAL     /opt/couchbase/bin/../lib/libplatform_so.so.0.1.0(_ZN9Couchbase6Thread12thread_entryEv+0xf) [0x7f74d6629000+0x1b5df]

2020-09-23T16:58:46.487410-07:00 CRITICAL     /opt/couchbase/bin/../lib/libplatform_so.so.0.1.0() [0x7f74d6629000+0x10947]

2020-09-23T16:58:46.487415-07:00 CRITICAL     /lib64/libpthread.so.0() [0x7f74d3e77000+0x7e65]