Fix the problem on destroy happening to fast

The problem  is visible in ckeditor#110

Author: bhugot

src/ckeditor/ckeditor.component.ts

@@ -238,7 +238,11 @@ export class CKEditorComponent implements AfterViewInit, OnDestroy, ControlValue
 	onTouched?: () => void;
 
 	private _data: string = null;
-
+	/**
+	 * If the component passed in ngOnDestroy to avoid the 
+	 * execution of the getEditorNamespace promise.
+	 */
+	private _destroyed = false;
 	/**
 	 * CKEditor 4 script url address. Script will be loaded only if CKEDITOR namespace is missing.
 	 *
@@ -251,11 +255,15 @@ export class CKEditorComponent implements AfterViewInit, OnDestroy, ControlValue
 
 	ngAfterViewInit(): void {
 		getEditorNamespace( this.editorUrl ).then( () => {
+			if( this._destroyed ){
+				return;
+			}
 			this.ngZone.runOutsideAngular( this.createEditor.bind( this ) );
 		} ).catch( window.console.error );
 	}
 
 	ngOnDestroy(): void {
+		this._destroyed = true;
 		this.ngZone.runOutsideAngular( () => {
 			if ( this.instance ) {
 				this.instance.destroy();