fix: werid validation on custom suffix omission

Author: plutack

components/forms/shorten-link-form-base.tsx

@@ -36,7 +36,7 @@ export function ShortenLinkFormBase({
     defaultValues: {
       name: "",
       link: "",
-      customSuffix: "",
+      customSuffix: undefined,
     },
   });
 

schemas/index.ts

@@ -27,7 +27,7 @@ export const shortenLinkSchema = z.object({
     .string()
     .min(3, { message: "Custom suffix is too short" })
     .optional()
-    .or(z.literal("")),
+    .or(z.undefined()),
 });
 
 export const changeCustomSuffixSchema = z.object({