Fix: VSE: Runtime error for change effect menu on non-effects

The "change" menu (accessible through C) would spit out an
error if hovering over the "Change effect type" menu when the
active strip was not an effect.

Pull Request: https://projects.blender.org/blender/blender/pulls/140692

scripts/startup/bl_ui/space_sequencer.py

@@ -660,8 +660,14 @@ class SEQUENCER_MT_change(Menu):
             del bpy_data_scenes_len
 
         layout.operator_context = 'INVOKE_DEFAULT'
-        layout.menu("SEQUENCER_MT_strip_effect_change")
-        layout.operator("sequencer.swap_inputs")
+        if strip.type in {
+            'CROSS', 'ADD', 'SUBTRACT', 'ALPHA_OVER', 'ALPHA_UNDER',
+            'GAMMA_CROSS', 'MULTIPLY', 'WIPE', 'GLOW',
+            'TRANSFORM', 'SPEED', 'MULTICAM', 'ADJUSTMENT',
+            'GAUSSIAN_BLUR',
+        }:
+            layout.menu("SEQUENCER_MT_strip_effect_change")
+            layout.operator("sequencer.swap_inputs")
         props = layout.operator("sequencer.change_path", text="Path/Files")
 
         if strip: