Fix NPE in NdefRecord parser.

Malformed Uri tags could cause this crash.

Bug: 7116323
Change-Id: I979d1512058f351df32dbd972b6ec5c108202da5
diff --git a/core/java/android/nfc/NdefRecord.java b/core/java/android/nfc/NdefRecord.java
index ed1c5b3..2d9dae9 100644
--- a/core/java/android/nfc/NdefRecord.java
+++ b/core/java/android/nfc/NdefRecord.java
@@ -688,7 +688,8 @@
                         }
                     } catch (FormatException e) {  }
                 } else if (Arrays.equals(mType, RTD_URI)) {
-                    return parseWktUri().normalizeScheme();
+                    Uri wktUri = parseWktUri();
+                    return (wktUri != null ? wktUri.normalizeScheme() : null);
                 }
                 break;