Hi ,

this message is produced in a routine which doesn't know the
file name (and  I found no easy way to change that), so
the only good improvement that I found is to print a stack trace
when it doesn't happen while processing a single OSM input file.
(mkgmap r3596).

@Steve: Maybe we can throw a different Exeption and catch that
in the higher routine which can decide if the hint
"The .osm file should be split into smaller pieces first."
makes sense or not?
BufferedImgFileWriter is used for so many different files...

Gerd