fixes #51651

src/vs/workbench/parts/files/browser/files.ts

@@ -52,7 +52,7 @@ export function getMultiSelectedResources(resource: URI | object, listService: I
 			const mainUriStr = URI.isUri(resource) ? resource.toString() : focus instanceof ExplorerItem ? focus.resource.toString() : undefined;
 			// If the resource is passed it has to be a part of the returned context.
 			// We only respect the selection if it contains the focused element.
-			if (selection.some(s => s.toString() === mainUriStr)) {
+			if (selection.some(s => URI.isUri(s) && s.toString() === mainUriStr)) {
 				return selection;
 			}
 		}