[BottomSheet] Added missing defensive checks to viewDragHelper calls

Resolves #1295
Resolves #1392

GIT_ORIGIN_REV_ID=cadca3f7e20c387562ab8088227f62f4cd6a40de
PiperOrigin-RevId: 323870916

(cherry picked from commit 3821664)

Author: matpag

lib/java/com/google/android/material/bottomsheet/BottomSheetBehavior.java

@@ -510,7 +510,7 @@ public boolean onTouchEvent(
     velocityTracker.addMovement(event);
     // The ViewDragHelper tries to capture only the top-most View. We have to explicitly tell it
     // to capture the bottom sheet in case it is not captured and the touch slop is passed.
-    if (action == MotionEvent.ACTION_MOVE && !ignoreEvents) {
+    if (viewDragHelper != null && action == MotionEvent.ACTION_MOVE && !ignoreEvents) {
       if (Math.abs(initialY - event.getY()) > viewDragHelper.getTouchSlop()) {
         viewDragHelper.captureChildView(child, event.getPointerId(event.getActionIndex()));
       }
@@ -1296,9 +1296,10 @@ void settleToState(@NonNull View child, int state) {
 
   void startSettlingAnimation(View child, int state, int top, boolean settleFromViewDragHelper) {
     boolean startedSettling =
-        settleFromViewDragHelper
-            ? viewDragHelper.settleCapturedViewAt(child.getLeft(), top)
-            : viewDragHelper.smoothSlideViewTo(child, child.getLeft(), top);
+        viewDragHelper != null
+            && (settleFromViewDragHelper
+                ? viewDragHelper.settleCapturedViewAt(child.getLeft(), top)
+                : viewDragHelper.smoothSlideViewTo(child, child.getLeft(), top));
     if (startedSettling) {
       setStateInternal(STATE_SETTLING);
       // STATE_SETTLING won't animate the material shape, so do that here with the target state.