fix doSetSync call for a first-time user sync flow

dist/bundle.es.js

@@ -2304,7 +2304,7 @@ function doGetSync(password) {
         }).then(({
           hash: walletHash,
           data
-        }) => dispatch(doSetSync(null, walletHash, data)));
+        }) => dispatch(doSetSync('', walletHash, data)));
       });
     });
   };

dist/bundle.js

@@ -3846,7 +3846,7 @@ function doGetSync(password) {
         }).then(function (_ref2) {
           var walletHash = _ref2.hash,
               data = _ref2.data;
-          return dispatch(doSetSync(null, walletHash, data));
+          return dispatch(doSetSync('', walletHash, data));
         });
       });
     });

src/redux/actions/sync.js

@@ -119,7 +119,7 @@ export function doGetSync(password) {
           // call sync_apply to get data to sync
           // first time sync. use any string for old hash
           Lbry.sync_apply({ password }).then(({ hash: walletHash, data }) =>
-            dispatch(doSetSync(null, walletHash, data))
+            dispatch(doSetSync('', walletHash, data))
           );
         });
     });