Running the script with percentile clipping as the rejection algorithm for Flat image integration results in the crash. Script works fine using default WSC or Min/Max for rejection. However, the default WSC rejection algorithm fails to remove stars present in my individual sky flat frames(I had only 4 flats on this run). So, changed to recommended settings in Vicent's tutorial ie percentile clipping and that choice results in the crash when the script reaches the the point where flat frame image integration is to run. Percentile clipping works fine when creating the master Flat without the script. I was able to get a satisfactory master flat using the script with the stars rejected by using min/max for rejection but I presume percentile clipping is preferred since it's the recommended rejection algorithm.