Issue #3774: Fixed an error when create a Tkinter menu item without command

and then remove it. Written by Guilherme Polo (gpolo). Ported r67082.

Lib/tkinter/__init__.py

@@ -1913,6 +1913,8 @@ class BaseWidget(Misc):
             cnf = _cnfmerge((cnf, kw))
         self.widgetName = widgetName
         BaseWidget._setup(self, master, cnf)
+        if self._tclCommands is None:
+            self._tclCommands = []
         classes = [(k, v) for k, v in cnf.items() if isinstance(k, type)]
         for k, v in classes:
             del cnf[k]
@@ -2648,21 +2650,20 @@ class Menu(Widget):
         """Add separator at INDEX."""
         self.insert(index, 'separator', cnf or kw)
     def delete(self, index1, index2=None):
-        """Delete menu items between INDEX1 and INDEX2 (not included)."""
+        """Delete menu items between INDEX1 and INDEX2 (included)."""
         if index2 is None:
             index2 = index1
-        cmds = []
-        (num_index1, num_index2) = (self.index(index1), self.index(index2))
-        if (num_index1 is not None) and (num_index2 is not None):
+
+        num_index1, num_index2 = self.index(index1), self.index(index2)
+        if (num_index1 is None) or (num_index2 is None):
+            num_index1, num_index2 = 0, -1
+
         for i in range(num_index1, num_index2 + 1):
             if 'command' in self.entryconfig(i):
                 c = str(self.entrycget(i, 'command'))
-                    if c in self._tclCommands:
-                        cmds.append(c)
-        self.tk.call(self._w, 'delete', index1, index2)
-        for c in cmds:
+                if c:
                     self.deletecommand(c)
-
+        self.tk.call(self._w, 'delete', index1, index2)
     def entrycget(self, index, option):
         """Return the resource value of an menu item for OPTION at INDEX."""
         return self.tk.call(self._w, 'entrycget', index, '-' + option)