'Fixes' the "curveprofile" case of #137870, by immediately crashing on nullptr access instead of allowing readfile code to further access memory detected as invalid (which would most likely lead to a crash later anyway). I don't think we can expect readfile code to gracefully abort at such a low-level error detection, not without using some form of exception handling at least? Otherwise the whole readfile code would have to constantly check for invalid flag in the Mains. Pull Request: https://projects.blender.org/blender/blender/pulls/138145