v.in.mapgen: print error message if fails, see https://trac.osgeo.org/grass/ticket/1065

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@42229 15284696-431f-4ddb-bdfa-cd5b030d7da7

scripts/v.in.mapgen/v.in.mapgen.py

@@ -122,10 +122,14 @@ def main():
 		if len(f) == 2:
 		    f.append('0')
 		points.append(f)
+        
 	if points != []:
 	    outf.write("L %d\n" % len(points))
 	    for point in points:
-		outf.write(" %.8f %.8f %.8f\n" % tuple(map(float,point)))
+                try:
+                    outf.write(" %.8f %.8f %.8f\n" % tuple(map(float, point)))
+                except ValueError:
+                    grass.fatal(_("An error occured on line '%s', exiting.") % line.strip())
     else:
         ## mapgen format.
 	points = []