Don't crash system process on empty onTuneFailed

This change:
- modifies internal programSelectorFromHal to return null instead of
  throwing NPE on empty input
- throws NPE on two of its usages where null is unexpected
- *does not* throw NPE on one usage where program selector is optional
  (onTuneFailed in RadioModule.java)

Bug: 147522441
Test: boots, but have no quick way to trigger onTuneFailed(Result::error, {})
Change-Id: I6317da3fbde2bce90079b61bb0839e893e1c4712
(cherry picked from commit dc8a5683a149b4f5ce3d9a9f6198fbe310547dbf)

services/core/java/com/android/server/broadcastradio/hal2/Convert.java

@@ -275,8 +275,18 @@ class Convert {
         return hwSel;
     }
 
-    static @NonNull ProgramSelector programSelectorFromHal(
+    private static boolean isEmpty(
             @NonNull android.hardware.broadcastradio.V2_0.ProgramSelector sel) {
+        if (sel.primaryId.type != 0) return false;
+        if (sel.primaryId.value != 0) return false;
+        if (sel.secondaryIds.size() != 0) return false;
+        return true;
+    }
+
+    static @Nullable ProgramSelector programSelectorFromHal(
+            @NonNull android.hardware.broadcastradio.V2_0.ProgramSelector sel) {
+        if (isEmpty(sel)) return null;
+
         ProgramSelector.Identifier[] secondaryIds = sel.secondaryIds.stream().
                 map(Convert::programIdentifierFromHal).map(Objects::requireNonNull).
                 toArray(ProgramSelector.Identifier[]::new);
@@ -364,7 +374,7 @@ class Convert {
                 collect(Collectors.toList());
 
         return new RadioManager.ProgramInfo(
-                programSelectorFromHal(info.selector),
+                Objects.requireNonNull(programSelectorFromHal(info.selector)),
                 programIdentifierFromHal(info.logicallyTunedTo),
                 programIdentifierFromHal(info.physicallyTunedTo),
                 relatedContent,
@@ -402,7 +412,7 @@ class Convert {
     public static @NonNull android.hardware.radio.Announcement announcementFromHal(
             @NonNull Announcement hwAnnouncement) {
         return new android.hardware.radio.Announcement(
-            programSelectorFromHal(hwAnnouncement.selector),
+            Objects.requireNonNull(programSelectorFromHal(hwAnnouncement.selector)),
             hwAnnouncement.type,
             vendorInfoFromHal(hwAnnouncement.vendorInfo)
         );