Throwing (and not catching) large errors in tests kills MozJS thread without printing the stack trace and the error message. This can happen when a JavaScript test assert fails and the message is over 64MB. The error message printed in the test log looks as follows:

[js_test:change_stream_pit_pre_images] exception: BufBuilder attempted to grow() to 377558926 bytes, past the 64MB limit.
[js_test:change_stream_pit_pre_images] exiting with code 1 

A developer is then left to wonder which test line has caused this.