Make #polyself a non-wizard-mode-exclusive command. When used in regular play, it will:

1. Cast the polymorph spell at yourself, if you know it.
2. Otherwise, attempt to activate a polymorph trap you are standing on.
3. Otherwise, fail like the #teleport command would when you are unable to teleport at will.

When you attempt to polymorph an item that has polymorph magic (wand/spell/potion of polymorph, tin of meat that may cause a polymorph when eaten, etc) it explodes and creates one or more monsters affiliated with polymorph magic, such as polymorph vortices (see YANI #3669), genetic engineers, or similar.

Convert the spell of polymorph to a form that polymorphs only monsters and never items.