MediaHiearchyManager: prevent NPE in updateTargetState()

For some reason, even after adding the checks for -1 in
`isCurrentlyInGuidedTransformation()`, there are still times when
`startHost` and/or `endHost` can be null, causing a NPE.

Fixes: 221754301
Test: N/A
Change-Id: I05d02ac7dcd6b0d8a850f9a8bbef8ce6205a8231

packages/SystemUI/src/com/android/systemui/media/MediaHierarchyManager.kt

@@ -741,10 +741,11 @@ class MediaHierarchyManager @Inject constructor(
      * Updates the bounds that the view wants to be in at the end of the animation.
      */
     private fun updateTargetState() {
-        if (isCurrentlyInGuidedTransformation() && !isCurrentlyFading()) {
+        var starthost = getHost(previousLocation)
+        var endHost = getHost(desiredLocation)
+        if (isCurrentlyInGuidedTransformation() && !isCurrentlyFading() && starthost != null &&
+            endHost != null) {
             val progress = getTransformationProgress()
-            var endHost = getHost(desiredLocation)!!
-            var starthost = getHost(previousLocation)!!
             // If either of the hosts are invisible, let's keep them at the other host location to
             // have a nicer disappear animation. Otherwise the currentBounds of the state might
             // be undefined
@@ -756,8 +757,8 @@ class MediaHierarchyManager @Inject constructor(
             val newBounds = endHost.currentBounds
             val previousBounds = starthost.currentBounds
             targetBounds = interpolateBounds(previousBounds, newBounds, progress)
-        } else {
-            val bounds = getHost(desiredLocation)?.currentBounds ?: return
+        } else if (endHost != null) {
+            val bounds = endHost.currentBounds
             targetBounds.set(bounds)
         }
     }