The Stolen Necklace-Brain teaser

Riddle 
A woman stole a necklace and put it in her pocket. However, the next day she found the necklace was gone, yet her pocket was not torn or broken, and nothing else was taken. How is this possible?

    The woman was a dreamer and dreamed about stealing the necklace. When she woke up, the necklace wasn't there because it never existed in reality.