Add AlarmInstance null check in AlarmActivity.onResume.

        final long instanceId = AlarmInstance.getId(getIntent().getData());

        mAlarmInstance = AlarmInstance.getInstance(getContentResolver(), instanceId);

        if (mAlarmInstance == null) {

            LogUtils.i(LOGTAG, "No alarm instance for instanceId: %d", instanceId);

            finish();

            return;

        }

        // Verify that the alarm is still firing before showing the activity

        if (mAlarmInstance.mAlarmState != AlarmInstance.FIRED_STATE) {

            LogUtils.i(LOGTAG, "Skip displaying alarm for instance: %s", mAlarmInstance);