Camera: don't dereference timestamp if it is missing

        entry = mNewFrame.find(ANDROID_SENSOR_TIMESTAMP);

        if (entry.count == 0) {

            ALOGE("No timestamp field in capture frame!");

        }

        } else if (entry.count == 1) {

            if (entry.data.i64[0] != mCaptureTimestamp) {

                ALOGW("Mismatched capture timestamps: Metadata frame %" PRId64 ","

                        " captured buffer %" PRId64,

                        entry.data.i64[0],

                        mCaptureTimestamp);

            }

        } else {

            ALOGE("Timestamp metadata is malformed!");

        }

        client->removeFrameListener(mCaptureId, mCaptureId + 1, this);

        mNewFrameReceived = false;