Fix comments can't be updated (microsoft#142013)

Fixes of microsoft#142012

Author: alexr00

src/vs/workbench/contrib/comments/browser/commentNode.ts

@@ -124,10 +124,7 @@ export class CommentNode extends Disposable {
 
 	private updateCommentBody(body: string | IMarkdownString) {
 		this._body.innerText = '';
-		if (this._md) {
-			this._body.removeChild(this._md);
-			this._md = undefined;
-		}
+		this._md = undefined;
 		if (typeof body === 'string') {
 			this._body.innerText = body;
 		} else {