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

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

Change-Id: I80e701693daa4f8a73e36c57febc087b21bafc83