Better trapping of command argument errors (backport from develbranch_6)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@40610 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/gui_modules/prompt.py

@@ -770,7 +770,10 @@ class GPromptSTC(GPrompt, wx.stc.StyledTextCtrl):
             except:
                 arg = ''
             
-            self.promptType = self.cmdDesc.get_param(arg)['prompt']
+            try:
+                self.promptType = self.cmdDesc.get_param(arg)['prompt']
+            except:
+                pass
             
             if event.GetKeyCode() == 61:
                 # autocompletion after '='