Sigh, actually display the error better.

plugin/cobol.py

@@ -55,7 +55,7 @@ def cobol_Renumber():
       try:
         last_line_no = int(lines[i][:6])
       except ValueError:
-          print('Malformed line (%d) - has non-numbers in columns 1-6' % i - 1)
+        print('Error: line %d has non-numbers in columns 1-6' % (i + 1))
         return
       if gap:
         delta = math.floor((last_line_no - gap['last_line_no']) /