Backport PR #427: Fix collaborators panel breaking on opening files without known extension (#451)

Co-authored-by: Michał Krassowski <[email protected]>

Author: meeseeksmachine

packages/collaboration/src/collaboratorspanel.tsx

@@ -166,7 +166,7 @@ export function Collaborator(props: {
     const fileTypes = props.docRegistry
       ?.getFileTypesForPath(path[1])
       ?.filter(ft => ft.icon !== undefined);
-    const icon = fileTypes ? fileTypes[0].icon! : fileIcon;
+    const icon = fileTypes?.length ? fileTypes[0].icon : fileIcon;
     const iconClass: string | undefined = fileTypes
       ? fileTypes[0].iconClass
       : undefined;