Occasionally getting wrong-type-argument for semantic overlays

Semantic is working fine a lot of the time, however, sometimes it gets
into a state where whenever I open any file where semantic is active, I
get spammed with thousands of these messages, for every other buffer
that's already open with semantic enabled:

Error: (wrong-type-argument symbolp #<overlay from 832 to 890 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 891 to 924 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 925 to 990 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 991 to 1047 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 1048 to 1096 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 1097 to 1153 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 1154 to 1229 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 1230 to 1301 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 1302 to 1343 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 1344 to 1402 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 1403 to 1454 in IndexRequest.java>)
Error: (wrong-type-argument symbolp #<overlay from 1455 to 1496 in IndexRequest.java>)
... etc etc etc hundreds more ...

I tried `debug-on-error` but it never shows a backtrace, is there some
way I can debug what's causing this? Usually I have to restart Emacs and
then it works okay for a while, then goes back to failing.

--
;; Lee

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