check return value of DmSyncStart

Author: paul-szczepanek-arm

features/FEATURE_BLE/targets/TARGET_CORDIO/source/CordioPalGap.cpp

@@ -1014,15 +1014,19 @@ ble_error_t Gap::periodic_advertising_create_sync(
         );
     }
 
-    DmSyncStart(
+    dmSyncId_t sync_id = DmSyncStart(
         advertising_sid,
         peer_address_type.value(),
         peer_address.data(),
         allowed_skip,
         sync_timeout
     );
 
+    if (sync_id == DM_SYNC_ID_NONE) {
         return BLE_ERROR_NONE;
+    } else {
+        return BLE_ERROR_INTERNAL_STACK_FAILURE;
+    }
 }
 
 ble_error_t Gap::cancel_periodic_advertising_create_sync()