Performing a pad abort before T-2:43 at LC-34 causes a crash at said time

[ThatRedMelon]

At T-2:43 seconds, a check is performed here, to see whether to hold the launch or not:

https://github.com/orbiternassp/NASSP/blob/d3d8e660b5f7b745c8a0037d8adc484c9d3248e7/Orbitersdk/samples/ProjectApollo/src_launch/LC34.cpp#L265-L277

The CutoffInterlock function then performs a set of checks as seen here:

https://github.com/orbiternassp/NASSP/blob/d3d8e660b5f7b745c8a0037d8adc484c9d3248e7/Orbitersdk/samples/ProjectApollo/src_launch/LC34.cpp#L775-L794

Which then finally leads into the umbilical check here:

https://github.com/orbiternassp/NASSP/blob/d3d8e660b5f7b745c8a0037d8adc484c9d3248e7/Orbitersdk/samples/ProjectApollo/src_launch/SCMUmbilical.cpp#L57-L62

This usually works as intended. But if a pad abort is performed before this time, the S-1B vessel is disconnected, but not recognised in the "UmbilicalConnected" variable. The function then continues, and tries to find the sib variable, which returns NULL, and crashes the simulation.