Don't try to use display of detached task to update insets

If insets overrides change on a detached task, it shouldn't
have an effect anyways, so don't try to access the display-content
(which will be null when detached)

Bug: 249151208
Test: atest NexusLauncherTests:com.android.launcher3.ui.TaplTestsLauncher3#testAppIconLaunchFromAllAppsFromHome
Change-Id: I97bbb569f99c4f7bdd7e865c9a8122fc6b49bc79

services/core/java/com/android/server/wm/WindowContainer.java

@@ -477,7 +477,10 @@ class WindowContainer<E extends WindowContainer> extends ConfigurationContainer<
             }
             mLocalInsetsSourceProviders.remove(insetsTypes[i]);
         }
-        mDisplayContent.getInsetsStateController().updateAboveInsetsState(true);
+        // Update insets if this window is attached.
+        if (mDisplayContent != null) {
+            mDisplayContent.getInsetsStateController().updateAboveInsetsState(true);
+        }
     }
 
     /**