Add extra nil check to details
Add extra nil check to details

Change-Id: Ia927aa99b7a02a4cc82a83ea2c54687e6ea2b942
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/210405
Auto-Submit: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Commit-Queue: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot