mutation field description now defaults to null rather that empty string

Author: christensenemc

src/mutation/__tests__/mutation.js

@@ -383,19 +383,19 @@ describe('mutationWithClientMutationId()', () => {
             fields: [
               {
                 name: 'simpleMutation',
-                description: ''
+                description: null
               },
               {
                 name: 'simpleMutationWithDescription',
                 description: 'Simple Mutation Description'
               },
               {
                 name: 'simpleMutationWithThunkFields',
-                description: ''
+                description: null
               },
               {
                 name: 'simplePromiseMutation',
-                description: ''
+                description: null
               },
             ]
           }

src/mutation/mutation.js

@@ -58,8 +58,13 @@ type MutationConfig = {
 export function mutationWithClientMutationId(
   config: MutationConfig
 ): GraphQLFieldConfig {
-  var {name, inputFields, outputFields, mutateAndGetPayload} = config;
-  var description = config.description != null ? config.description : '';
+  var {
+    name,
+    inputFields,
+    outputFields,
+    mutateAndGetPayload,
+    description
+  } = config;
   var augmentedInputFields = () => ({
     ...resolveMaybeThunk(inputFields),
     clientMutationId: {