Fix faded dashcards when switching dashboards

frontend/src/metabase/dashboard/dashboard.js

@@ -476,6 +476,7 @@ const cardDurations = handleActions({
 }, {});
 
 const parameterValues = handleActions({
+    [INITIALIZE]: { next: () => ({}) },
     [SET_PARAMETER_VALUE]: { next: (state, { payload: { id, value }}) => i.assoc(state, id, value) },
     [REMOVE_PARAMETER]: { next: (state, { payload: { id }}) => i.dissoc(state, id) }
 }, {});

frontend/src/metabase/dashboard/selectors.js

@@ -83,6 +83,10 @@ export const getParameterTarget = createSelector(
 export const getMappingsByParameter = createSelector(
     [getMetadata, getDashboardComplete],
     (metadata, dashboard) => {
+        if (!dashboard) {
+            return {};
+        }
+
         let mappingsByParameter = {};
         let countsByParameter = {};
         let mappings = [];