Fix crash in tracking spring animations when toValue node is detached (#55734)

Summary:
This PR fixes an Android Native Animated crash in tracking + spring animations when the tracked `toValue` node is detached.

In `TrackingAnimatedNode.update`, if the tracked node could not be resolved, we used to write `toValue = null` into `animationConfig`. `SpringAnimation.resetConfig` expects `toValue` to be a number, so this could crash with `NullPointerException: null cannot be cast to non-null type kotlin.Number`

This can happen in real apps during graph teardown (for example unmount/re-render/navigation transitions), where tracking may still update for a transient frame after the tracked node has been detached.

Fix:
- Do not propagate null `toValue` from `TrackingAnimatedNode`.
- If the tracked node is missing, fallback to the driven value node’s current value.
- If both nodes are unavailable, return safely.

This PR also adds a regression test.

## Changelog:

[ANDROID] [FIXED] - Prevent Native Animated tracking spring crash when tracked `toValue` node is detached.

Pull Request resolved: #55734

Test Plan:
Added regression test `NativeAnimatedNodeTraversalTest.testTrackingSpringDoesNotCrashWhenToValueNodeIsDetached`
- On a test-only commit (without the fix), the new test fails with: `NullPointerException: null cannot be cast to non-null type kotlin.Number`
- On this PR (with the fix), test pass.

Reviewed By: christophpurrer

Differential Revision: D94697059

Pulled By: zeyap

fbshipit-source-id: c8f1f619c34ce7887d6f9bfb42a035d41d6a063a

Author: kmsbernard

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/animated/TrackingAnimatedNode.kt

@@ -25,7 +25,11 @@ internal class TrackingAnimatedNode(
     if (valAnimatedNode != null) {
       animationConfig.putDouble("toValue", valAnimatedNode.getValue())
     } else {
-      animationConfig.putNull("toValue")
+      val drivenNode = nativeAnimatedNodesManager.getNodeById(valueNode) as? ValueAnimatedNode
+      if (drivenNode == null) {
+        return
+      }
+      animationConfig.putDouble("toValue", drivenNode.getValue())
     }
     nativeAnimatedNodesManager.startAnimatingNode(animationId, valueNode, animationConfig, null)
   }

packages/react-native/ReactAndroid/src/test/java/com/facebook/react/animated/NativeAnimatedNodeTraversalTest.kt

@@ -1370,6 +1370,44 @@ class NativeAnimatedNodeTraversalTest {
     assertThat(previousValue).isEqualTo(1.5)
   }
 
+  @Test
+  fun testTrackingSpringDoesNotCrashWhenToValueNodeIsDetached() {
+    val springConfig: JavaOnlyMap =
+        JavaOnlyMap.of(
+            "type",
+            "spring",
+            "stiffness",
+            230.2,
+            "damping",
+            22.0,
+            "mass",
+            1.0,
+            "initialVelocity",
+            0.0,
+            "restSpeedThreshold",
+            0.001,
+            "restDisplacementThreshold",
+            0.001,
+            "overshootClamping",
+            false,
+        )
+
+    createAnimatedGraphWithTrackingNode(springConfig)
+
+    nativeAnimatedNodesManager.setAnimatedNodeValue(1, 1.0)
+    nativeAnimatedNodesManager.runUpdates(nextFrameTime())
+
+    nativeAnimatedNodesManager.disconnectAnimatedNodes(1, 2)
+    nativeAnimatedNodesManager.dropAnimatedNode(1)
+
+    nativeAnimatedNodesManager.runUpdates(nextFrameTime())
+
+    val trackedNode = nativeAnimatedNodesManager.getNodeById(3) as? ValueAnimatedNode
+    assertThat(trackedNode).isNotNull
+    val trackedValue = checkNotNull(trackedNode).getValue()
+    assertThat(trackedValue.isNaN()).isFalse
+  }
+
   companion object {
     private const val FRAME_LEN_NANOS: Long = 1000000000L / 60L
     private const val INITIAL_FRAME_TIME_NANOS: Long = 14599233201256L /* random */