Camera: add proper nullptr check

Test: CTS
Bug: 64118349
Change-Id: I2fd5c3f32d4e13560a88f4657c4f25faedd869ba
diff --git a/services/camera/libcameraservice/device3/Camera3Device.cpp b/services/camera/libcameraservice/device3/Camera3Device.cpp
index 6421695..69b1d7d 100644
--- a/services/camera/libcameraservice/device3/Camera3Device.cpp
+++ b/services/camera/libcameraservice/device3/Camera3Device.cpp
@@ -2350,7 +2350,9 @@
 
     mErrorCause = errorCause;
 
-    mRequestThread->setPaused(true);
+    if (mRequestThread != nullptr) {
+        mRequestThread->setPaused(true);
+    }
     internalUpdateStatusLocked(STATUS_ERROR);
 
     // Notify upstream about a device error