explorer: do not allow to creatae a new file / folder while in the process of creating a new file

fixes #47606

src/vs/workbench/parts/files/common/explorerModel.ts

@@ -378,13 +378,14 @@ export class ExplorerItem {
 /* A helper that can be used to show a placeholder when creating a new stat */
 export class NewStatPlaceholder extends ExplorerItem {
 
+	public static NAME = '';
 	private static ID = 0;
 
 	private id: number;
 	private directoryPlaceholder: boolean;
 
 	constructor(isDirectory: boolean, root: ExplorerItem) {
-		super(URI.file(''), root, false, false, '');
+		super(URI.file(''), root, false, false, NewStatPlaceholder.NAME);
 
 		this.id = NewStatPlaceholder.ID++;
 		this.isDirectoryResolved = isDirectory;

src/vs/workbench/parts/files/electron-browser/fileActions.ts

@@ -391,6 +391,10 @@ export class BaseNewAction extends BaseFileAction {
 		if (!folder) {
 			return TPromise.wrapError(new Error('Invalid parent folder to create.'));
 		}
+		if (!!folder.getChild(NewStatPlaceholder.NAME)) {
+			// Do not allow to creatae a new file/folder while in the process of creating a new file/folder #47606
+			return TPromise.as(new Error('Parent folder is already in the process of creating a file'));
+		}
 
 		return this.tree.reveal(folder, 0.5).then(() => {
 			return this.tree.expand(folder).then(() => {