ensure to register component instance with id

src/client/js/components/Page.jsx

@@ -29,7 +29,7 @@ class Page extends React.Component {
   }
 
   componentWillMount() {
-    this.props.appContainer.registerComponentInstance(this);
+    this.props.appContainer.registerComponentInstance('Page', this);
   }
 
   /**

src/client/js/components/PageEditor.jsx

@@ -62,7 +62,7 @@ class PageEditor extends React.Component {
   }
 
   componentWillMount() {
-    this.props.appContainer.registerComponentInstance(this);
+    this.props.appContainer.registerComponentInstance('PageEditor', this);
 
     // initial rendering
     this.renderPreview(this.state.markdown);

src/client/js/components/PageEditorByHackmd.jsx

@@ -33,7 +33,7 @@ class PageEditorByHackmd extends React.Component {
   }
 
   componentWillMount() {
-    this.props.appContainer.registerComponentInstance(this);
+    this.props.appContainer.registerComponentInstance('PageEditorByHackmd', this);
   }
 
   /**

src/client/js/components/PageStatusAlert.jsx

@@ -31,7 +31,7 @@ class PageStatusAlert extends React.Component {
   }
 
   componentWillMount() {
-    this.props.appContainer.registerComponentInstance(this);
+    this.props.appContainer.registerComponentInstance('PageStatusAlert', this);
   }
 
   refreshPage() {

src/client/js/services/AppContainer.js

@@ -131,28 +131,27 @@ export default class AppContainer extends Container {
 
   /**
    * Register React component instance
+   * @param {string} id
    * @param {object} instance React component instance
    */
-  registerComponentInstance(instance) {
+  registerComponentInstance(id, instance) {
     if (instance == null) {
       throw new Error('The specified instance must not be null');
     }
 
-    const className = instance.constructor.name;
-
-    if (this.componentInstances[className] != null) {
-      throw new Error('The specified instance couldn\'t register because the same type object has already been registered');
+    if (this.componentInstances[id] != null) {
+      throw new Error('The specified instance couldn\'t register because the same id has already been registered');
     }
 
-    this.componentInstances[className] = instance;
+    this.componentInstances[id] = instance;
   }
 
   /**
    * Get registered React component instance
-   * @param {string} className
+   * @param {string} id
    */
-  getComponentInstance(className) {
-    return this.componentInstances[className];
+  getComponentInstance(id) {
+    return this.componentInstances[id];
   }
 
   getOriginRenderer() {