fix: add type guard to prevent crash with 'constructor' folder name

Fixes #861

When a folder is named 'constructor', getIconForFolder returns an object
(Object.prototype.constructor) instead of a string, causing a runtime error
when calling .indexOf() on it. Added a type check to ensure the icon is a
string before processing.

Co-authored-by: Brendan Kellam <brendan-kellam@users.noreply.github.com>

Author: github-actions[bot]

packages/web/src/app/components/vscodeFolderIcon.tsx

@@ -13,7 +13,7 @@ interface VscodeFolderIconProps {
 export const VscodeFolderIcon = ({ folderName, className }: VscodeFolderIconProps) => {
     const iconName = useMemo(() => {
         const icon = getIconForFolder(folderName);
-        if (icon) {
+        if (icon && typeof icon === 'string') {
             const iconName = `vscode-icons:${icon.substring(0, icon.indexOf('.')).replaceAll('_', '-')}`;
                 return iconName;
         }