feat: warn when json validator does not find a content type in the request

src/validator/validator.ts

@@ -72,6 +72,8 @@ export const validator = <
     switch (target) {
       case 'json':
         if (!contentType || !jsonRegex.test(contentType)) {
+          const message = 'missing Content-Type header "application/json"'
+          throw new HTTPException(415, { message })
           break
         }
         try {
@@ -86,6 +88,8 @@ export const validator = <
           !contentType ||
           !(multipartRegex.test(contentType) || urlencodedRegex.test(contentType))
         ) {
+          const message = 'missing Content-Type header "application/x-www-form-encoded"'
+          throw new HTTPException(415, { message })
           break
         }