Guard against no payment app

Bug: 25990521
Change-Id: I3307fb197d1a38ff759628bf72f6b7e4afcb8001
diff --git a/src/com/android/settings/nfc/PaymentSettings.java b/src/com/android/settings/nfc/PaymentSettings.java
index 42545b9..985a1e6 100644
--- a/src/com/android/settings/nfc/PaymentSettings.java
+++ b/src/com/android/settings/nfc/PaymentSettings.java
@@ -115,8 +115,10 @@
                 PaymentBackend paymentBackend = new PaymentBackend(mContext);
                 paymentBackend.refresh();
                 PaymentAppInfo app = paymentBackend.getDefaultApp();
-                mSummaryLoader.setSummary(this, mContext.getString(R.string.payment_summary,
-                        app.label));
+                if (app != null) {
+                    mSummaryLoader.setSummary(this, mContext.getString(R.string.payment_summary,
+                            app.label));
+                }
             }
         }
     }