d.mon: be less verbose, modules usually prints error message already

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@65902 15284696-431f-4ddb-bdfa-cd5b030d7da7

display/d.mon/render_cmd.py

@@ -37,7 +37,7 @@ def render(cmd, mapfile):
     try:
         grass.run_command(cmd[0], env=env, **cmd[1])
     except Exception as e:
-        grass.fatal("Unable to render: {}".format(e))
+        grass.debug(1, "Unable to render: {}".format(e))
 
 # update cmd file
 def update_cmd_file(cmd_file, cmd, mapfile):