[mkgmap-dev] Commit r4450: Produce better error message when input-file is a directory

Version mkgmap-r4450 was committed by gerd on Thu, 13 Feb 2020 Produce better error message when input-file is a directory This also prevents a possible StringIndexOutOfBoundsException http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4450