fix: change optional to nullable in validation

server/routers/contentstack/contactConfig/output.ts

@@ -55,6 +55,6 @@ export type ContactConfigData = z.infer<typeof validateContactConfigSchema>
 export type ContactConfig = ContactConfigData["all_contact_config"]["items"][0]
 
 export type ContactFields = {
-  display_text?: string
+  display_text: string | null
   contact_field: string
 }