Improve error message in WMS#isInTouchMode

Fix: 279962497
Test: m
Change-Id: Ibddc76bc27809dd449989b31f77163759d030b84

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

@@ -3905,8 +3905,9 @@ public class WindowManagerService extends IWindowManager.Stub
         synchronized (mGlobalLock) {
             final DisplayContent displayContent = mRoot.getDisplayContent(displayId);
             if (displayContent == null) {
-                throw new IllegalStateException("No touch mode is defined for displayId {"
-                        + displayId + "}");
+                throw new IllegalStateException("Failed to retrieve the touch mode state for"
+                        + "display {" + displayId + "}: display is not registered in "
+                        + "WindowRootContainer");
             }
             return displayContent.isInTouchMode();
         }