A defendant watched a liquor store furtively for some time, planning to hold it up. He bought a realistic-looking toy gun for the job. One night, just before the store's closing time, he drove to the store, opened the front door and entered. He reached in his pocket for the toy gun, but he became frightened and began to move back toward the front door. However, the shopkeeper had seen the butt of the gun. Fearing a holdup, the shopkeeper produced a gun from under the counter, pointed it at the defendant, and yelled, ‘ Stop!'' The defendant ran to the door and the toy gun fell from his pocket. The shopkeeper fired. The shot missed the defendant, but struck and killed a passerby outside the store. A statute in the jurisdiction defines burglary as ‘ breaking and entering any building or structure with the intent to commit a felony or to steal therein.'' On a charge of burglary, the defendant's best defense would be that