Clear scroll timer when component unmount (#867)

src/components/node.js

@@ -161,6 +161,17 @@ class Node extends React.Component {
     if (this.props.node != prevProps.node) this.updateScroll()
   }
 
+  /**
+   * There is a corner case, that some nodes are unmounted right after they update
+   * Then, when the timer execute, it will throw the error
+   * `findDOMNode was called on an unmounted component`
+   * We should clear the timer from updateScroll here
+   */
+
+  componentWillUnmount = () => {
+    clearTimeout(this.scrollTimer)
+  }
+
   /**
    * Update the scroll position after a change as occured if this is a leaf
    * block and it has the selection's ending edge. This ensures that scrolling
@@ -182,7 +193,7 @@ class Node extends React.Component {
 
     // The native selection will be updated after componentDidMount or componentDidUpdate.
     // Use setTimeout to queue scrolling to the last when the native selection has been updated to the correct value.
-    setTimeout(() => {
+    this.scrollTimer = setTimeout(() => {
       const el = ReactDOM.findDOMNode(this)
       const window = getWindow(el)
       const native = window.getSelection()