camera: Fix NPE in FOV test

Bug: 8484377
Change-Id: I66c0cc41450f403cf59533feded4dec85ba1b948
diff --git a/apps/CtsVerifier/src/com/android/cts/verifier/camera/fov/PhotoCaptureActivity.java b/apps/CtsVerifier/src/com/android/cts/verifier/camera/fov/PhotoCaptureActivity.java
index fdd5597..913ff4f 100644
--- a/apps/CtsVerifier/src/com/android/cts/verifier/camera/fov/PhotoCaptureActivity.java
+++ b/apps/CtsVerifier/src/com/android/cts/verifier/camera/fov/PhotoCaptureActivity.java
@@ -120,9 +120,11 @@
             @Override
             public void onClick(View v) {
                 // Stop camera until preview sizes have been obtained.
-                mCamera.stopPreview();
-                mCamera.release();
-                mCamera = null;
+                if (mCamera != null) {
+                    mCamera.stopPreview();
+                    mCamera.release();
+                    mCamera = null;
+                }
 
                 mPreviewSizeCamerasToProcess.clear();
                 mPreviewSizes =  new Size[Camera.getNumberOfCameras()];