Sometimes slurm (on some clusters) fails to exit when there is a nan - this means the program ends but does not exit, which is annoying and wastes resources.

The problem is with OpenMP - it works if you run with only one thread. The solution seems to be that the master thread needs to call the exit, but then we need to make sure that it is not only the master thread that can find nan to exit - we want it to exit for nan on any thread, and also we still want the thread that finds the nan to write out the data of where it is.