refactor: fix all lint errors and improve code quality

src/routes/signup/+page.server.ts

@@ -38,9 +38,9 @@ export const actions: Actions = {
     try {
       sanitizedName = sanitizeString(name, 100);
       sanitizedUsername = sanitizeUsername(username);
-    } catch (error) {
-      return fail(400, { error: 'Invalid input', name, username });
-    }
+  } catch {
+    return fail(400, { error: 'Invalid input', name, username });
+  }
 
     if (!sanitizedName) {
       return fail(400, { error: 'Name is required', name, username });

src/routes/signup/+page.svelte

@@ -79,7 +79,7 @@
           </div>
         </div>
 
-        {#each data.oauthProviders as provider}
+        {#each data.oauthProviders as provider (provider.id)}
           <Button
             type="button"
             variant="outline"