docs(@nestjs) update mongoose example

Author: kamilmysliwiec

examples/06-mongoose/src/modules/cats/cats.service.ts

@@ -1,7 +1,6 @@
 import { Model } from 'mongoose';
 import { Component, Inject } from '@nestjs/common';
 import { Cat } from './interfaces/cat.interface';
-import { CatsModule } from './cats.module';
 import { CreateCatDto } from './dto/create-cat.dto';
 
 @Component()
@@ -10,8 +9,8 @@ export class CatsService {
     @Inject('CatModelToken') private readonly catModel: Model<Cat>) {}
 
   async create(createCatDto: CreateCatDto): Promise<Cat> {
-    const cat = new this.catModel(createCatDto);
-    return await cat.save();
+    const createdCat = new this.catModel(createCatDto);
+    return await createdCat.save();
   }
 
   async findAll(): Promise<Cat[]> {

examples/06-mongoose/src/modules/database/database.providers.ts

@@ -3,7 +3,7 @@ import * as mongoose from 'mongoose';
 export const databaseProviders = [
   {
     provide: 'DbConnectionToken',
-    useFactory: async () => {
+    useFactory: async (): Promise<mongoose.Connection> => {
       (mongoose as any).Promise = global.Promise;
       return await mongoose.connect('mongodb://localhost/nest', {
         useMongoClient: true,