Avoid NPE if buffer contains a null am: 6276f53a12 am: f726d86389 am: da52a888d4 am: 9a5a085314 am: bba15ec093

Original change: https://android-review.googlesource.com/c/platform/tools/loganalysis/+/2020975

Change-Id: I81e0487ce0337a3d0f80d3ec9874fa3c3a144689