Revert "Fix: 'A | (empty)' was not errored and A was executed." for #100
Revert "Fix: 'A | (empty)' was not errored and A was executed." for #100

Because 'A &' caused an error.
This reverts commit b50461465636a97b8cb0c40ba8b1eaaa580a0e13.

tsuyoshicho/nyagos,hattya/nyagos,hattya/nyagos,hattya/nyagos,zetamatta/nyagos,tyochiai/nyagos,nocd5/nyagos