🐛 fix plotly#1098 : also persist 0, empty string etc

fixes plotly#1098 Persistence does not work for Input components when 0 is entered

Author: eddy-geek

dash-renderer/src/persistence.js

@@ -319,7 +319,7 @@ export function recordUiEdit(layout, newProps, dispatch) {
 
     forEach(persistedProp => {
         const [propName, propPart] = persistedProp.split('.');
-        if (newProps[propName]) {
+        if (newProps[propName] !== undefined) {
             const storage = getStore(persistence_type, dispatch);
             const {extract} = getTransform(element, propName, propPart);