fix(protocol): request header contentType

src/core/helpers/protocol/network/request.js

@@ -78,6 +78,7 @@ export const request = {
     type: Object,
     validator (value, params) {
       params.header = value || {}
+      params.header['content-type'] = params.header['content-type'] || 'application/json'
     }
   },
   dataType: {
@@ -93,4 +94,4 @@ export const request = {
       params.responseType = Object.values(responseType).indexOf(value) < 0 ? responseType.TEXT : value
     }
   }
-}
+}