refactor(constants): add ENTITIES constant and replace magic strings in editor reducer and inspector

app/components/Inspector.jsx

@@ -1,6 +1,6 @@
-import R from 'ramda';
 import React from 'react';
 import Widgets from './InspectorWidgets';
+import * as ENTITIES from '../constants/entities';
 
 const styles = {
   container: {
@@ -48,21 +48,23 @@ class Inspector extends React.Component {
     } else if (selection.length === 1) {
       const entity = (selection[0].entity);
       switch (entity) {
-        default:
-        case 'Node':
+        case ENTITIES.NODE:
           this.widgets = [
             new Widgets.HintWidget({
               text: 'There are no properties for the selected node.',
             }),
           ];
           break;
-        case 'Link':
+        case ENTITIES.LINK:
           this.widgets = [
             new Widgets.HintWidget({
               text: 'Links have not any properties.',
             }),
           ];
           break;
+        default:
+          this.widgets = [];
+          break;
       }
     } else {
       this.widgets = [

app/constants/entities.js

@@ -0,0 +1,3 @@
+export const NODE = 'Node';
+export const LINK = 'Link';
+export const PIN = 'Pin';

app/reducers/editor.js

@@ -7,6 +7,7 @@ import {
   EDITOR_SET_MODE,
   EDITOR_SET_SELECTED_NODETYPE,
 } from '../actionTypes';
+import * as ENTITIES from '../constants/entities';
 
 const addSelection = (entityName, action, state) => {
   const select = {
@@ -25,9 +26,9 @@ export const editor = (state = {}, action) => {
         linkingPin: null,
       });
     case EDITOR_SELECT_NODE:
-      return addSelection('Node', action, state);
+      return addSelection(ENTITIES.NODE, action, state);
     case EDITOR_SELECT_LINK:
-      return addSelection('Link', action, state);
+      return addSelection(ENTITIES.LINK, action, state);
     case EDITOR_SELECT_PIN:
       return R.set(R.lensProp('linkingPin'), action.payload.id, state);
     case EDITOR_SET_MODE: