I don't know what caused it, since I don't know what the code is trying to do, but when loading up the lab with a debug build I always got an assertion error
from within a vector class because the index was out of bounds (the vector was empty).
Since the code is trying to access the first element to get the starting address of the vector (bad bad thing to do without checking the vector first) this caused the assertion.
I changed the code to do the length check first and only try to get the address of the vector if it actually contains any elements (otherwise the entire function is not doing anything anyway).
Patch attached.
[attachment deleted by MSC