@OrderBy bug

[SergeShkurko]

When i add

@OrderBy() orderBy: OrderByItem[],

in my method

import {
  ObjectType,
  Field,
  Ctx,
  Arg,
  OrderBy,
  OrderByItem,
  PaginationResponse,
  Root,
} from 'graphql-schema-decorator/lib'
import NewsSchema from 'news/schema'

@ObjectType({
  description: 'News',
})
export default class NewsQuery {
  @Field({
    type: NewsSchema,
    pagination: true,
  })
  public all?(
    @Ctx() context: any,
    @Root() root: any,
    @Arg({ name: 'offset' }) offset: number,
    @Arg({ name: 'limit' }) limit: number,
    @OrderBy() orderBy: OrderByItem[],
  ): NewsSchema[] {
    console.log(context, offset, limit, orderBy[0])

    const result = [
      {
        image: 'image 1',
        title: 'title 1',
        description: 'description 1',
        content: 'content 1',
        timestamp: new Date().toISOString(),
      },
      {
        image: 'image 2',
        title: 'title 2',
        description: 'description 2',
        content: 'content 2',
        timestamp: new Date().toISOString(),
      },
      {
        image: 'image 3',
        title: 'title 3',
        description: 'description 3',
        content: 'content 3',
        timestamp: new Date().toISOString(),
      },
    ]

    return new PaginationResponse<NewsSchema>(3, result, null)
  }
}

Without @OrderBy() orderBy: OrderByItem[], work normally

node give me error:

/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/order-by.type-factory.js:56
                    if (fieldReturnType.prototype == null) {
                                        ^

TypeError: Cannot read property 'prototype' of undefined
    at fieldMetadataList.forEach.def (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/order-by.type-factory.js:56:41)
    at Array.forEach ()
    at Function.orderByFactory (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/order-by.type-factory.js:54:35)
    at Object.fieldTypeFactory (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/field.type-factory.js:191:55)
    at fieldMetadataList.reduce (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/object.type-factory.js:37:40)
    at Array.reduce ()
    at metadata_builder_1.getMetadataBuilder.buildObjectTypeMetadata.map.metadata (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/object.type-factory.js:36:42)
    at Array.map ()
    at Object.objectTypeFactory (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/object.type-factory.js:17:10)
    at convertType (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/field.type-factory.js:44:48)
    at Object.fieldTypeFactory (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/field.type-factory.js:190:23)
    at fieldMetadatas.reduce (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/schema.type-factory.js:40:63)
    at Array.reduce ()
    at metadatas.map.metadata (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/schema.type-factory.js:39:31)
    at Array.map ()
    at getEntryObject (/home/node/app/node_modules/graphql-schema-decorator/lib/type-factory/schema.type-factory.js:36:30)

Lib version: 1.0.0-alpha9
Node: 9.5.0