gcmd.RunCommand needs to return error messages in this context

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@41151 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/gui_modules/render.py

@@ -148,7 +148,8 @@ class Layer(object):
             if self.type == 'command':
                 read = False
                 for c in self.cmd:
-                    ret = gcmd.RunCommand(c[0],
+                    ret, msg = gcmd.RunCommand(c[0],
+                                          getErrorMsg = True,
                                           quiet = True,
                                           **c[1])
                     if ret != 0: