Make grid editor file reading more robust.

libmproxy/console/grideditor.py

@@ -291,10 +291,14 @@ class GridEditor(common.WWrap):
             return None
 
     def read_file(self, p, unescaped=False):
+        if p:
+            try:
                 p = os.path.expanduser(p)
                 d = file(p, "r").read()
                 self.walker.set_current_value(d, unescaped)
                 self.walker._modified()
+            except IOError, v:
+                return str(v)
 
     def keypress(self, size, key):
         if self.walker.editing: