CallStyle: add missing null check for icon

Bug: 329288442
Flag: ACONFIG com.android.systemui.new_call_style_action_layout NEXTFOOD
Test: none
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:bfc6a51b9b82708154b2353c38c4fce562fe023e)
Merged-In: I5d0773881171dd233411edc19d3988789dac4259
Change-Id: I5d0773881171dd233411edc19d3988789dac4259

core/java/com/android/internal/widget/EmphasizedNotificationButton.java

diff --git a/core/java/com/android/internal/widget/EmphasizedNotificationButton.java b/core/java/com/android/internal/widget/EmphasizedNotificationButton.java
index 3e065bf..01b4569 100644
--- a/core/java/com/android/internal/widget/EmphasizedNotificationButton.java
+++ b/core/java/com/android/internal/widget/EmphasizedNotificationButton.java
@@ -171,7 +171,9 @@
             return;
         }
 
-        prepareIcon(icon);
+        if (icon != null) {
+            prepareIcon(icon);
+        }
 
         mIconToGlue = icon;
         mGluePending = true;