[mkgmap-dev] Commit r4807: fix possible NPE when --keep-going is used in combination with an input file that doesn't exist

Version mkgmap-r4807 was committed by gerd on Tue, 14 Sep 2021 fix possible NPE when --keep-going is used in combination with an input file that doesn't exist http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4807