Fix test bug where launcher throws NPE because it isnt loaded yet.

Bug: 140635319
Change-Id: Iea90c6816c670d58acf79114fc725602ddc9d0b1
diff --git a/tests/src/com/android/launcher3/compat/PromiseIconUiTest.java b/tests/src/com/android/launcher3/compat/PromiseIconUiTest.java
index 7ef946d..efbd9c9 100644
--- a/tests/src/com/android/launcher3/compat/PromiseIconUiTest.java
+++ b/tests/src/com/android/launcher3/compat/PromiseIconUiTest.java
@@ -48,6 +48,7 @@
     public void setUp() throws Exception {
         super.setUp();
         mDevice.pressHome();
+        waitForLauncherCondition("Launcher didn't start", launcher -> launcher != null);
         waitForState("Launcher internal state didn't switch to Home", LauncherState.NORMAL);
         mSessionId = -1;
     }