Filter dead keys in tree keyboard navigation

Fixes #80741

src/vs/base/browser/ui/tree/abstractTree.ts

@@ -657,6 +657,7 @@ class TypeFilterController<T, TFilterData> implements IDisposable {
 
 		const onKeyDown = Event.chain(domEvent(this.view.getHTMLElement(), 'keydown'))
 			.filter(e => !isInputElement(e.target as HTMLElement) || e.target === this.filterOnTypeDomNode)
+			.filter(e => e.key !== 'Dead')
 			.map(e => new StandardKeyboardEvent(e))
 			.filter(this.keyboardNavigationEventFilter || (() => true))
 			.filter(() => this.automaticKeyboardNavigation || this.triggered)