Check that HD record exists or place in try/catch block

[cerebis]

bin3C/mzd/contact_map.py

Line 537 in 76ad2a9

if 'SO' not in bam.header['HD'] or bam.header['HD']['SO'] != 'queryname':

This will produce an uncaught exception if the 'HD' record does not existing the BAM file.

We need to either check for 'HD' or place this call in a try/catch KeyError