Fix potential NULL dereference in Visualizer effect am: 874f9e0b8e am: f060479b9a am: bcc7230bb9 am: f4a63f6765 am: ecfd198cda am: bae68c9e15 am: d36ebed01e am: 1b963dc33c am: b4842ae2d4 am: 59f22c99fe am: 7fc03ff680 am: 7b8a3a9fa8 am: d3af3e9e0c am: d48a0e67db
am: 40860e15eb

Change-Id: I098a7864955b2ab2b66d042efd4b0480cf28455f