Error reducer: fix handling of appending errors.

Apparently if the payload is an instante of an Error object, payload creator won't
be called.

Info: https://redux-actions.js.org/api/createaction

src/store/actions.ts

@@ -169,7 +169,7 @@ export const performSync = createAction(
 export const appendError = createAction(
   "APPEND_ERROR",
   (error: Error | Error[]) => {
-    return Array.isArray(error) ? error : [error];
+    return error;
   }
 );
 

src/store/reducers.ts

@@ -215,7 +215,11 @@ export const errorsReducer = handleActions(
       return state;
     },
     [actions.appendError.toString()]: (state: List<Error>, action: Action<any>) => {
-      return state.push(...action.payload);
+      if (Array.isArray(action.payload)) {
+        return state.push(...action.payload);
+      } else {
+        return state.push(action.payload);
+      }
     },
     [actions.clearErros.toString()]: (state: List<Error>, _action: Action<any>) => {
       return state.clear();