Fix potential NULL dereference in Visualizer effect am: 874f9e0b8e am: f060479b9a am: bcc7230bb9 am: f4a63f6765 am: ecfd198cda am: bae68c9e15 am: d36ebed01e
am: 1b963dc33c

Change-Id: I4fa9bb3b9c7fbf722e33a6be08c35989e45442b1