Comment 6 for bug 1786349

We don't know a lot here, but I think the error log tells us:

1) it crashes on a null pointer access
2) it is in a co-routine which takes a TOOL_EVENT as a parameter
3) the null pointer access is quite near the beginning of the routine

There are 4 routines that fit that description; one of them makes not pointer dereferences and one of which check all pointers near the start.

I've added extra safety checks to the other two.