Schematics error: Cannot read property 'length' of undefined

Bug Report

Current behavior

If you generate a module with nest g mo core/module in order to have a module called DatabaseModule into your CoreModule then throws an error like:

TypeError: Cannot read property 'length' of undefined
    at MetadataManager.insertSymbolToMetadata (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\dist\utils\metadata.manager.js:104:33)
    at MetadataManager.insert (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\dist\utils\metadata.manager.js:41:25)
    at ModuleMetadataDeclarator.declare (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\dist\utils\module-metadata.declarator.js:7:34)
    at ModuleDeclarator.declare (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\dist\utils\module.declarator.js:14:33)
    at G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\dist\lib\module\module.factory.js:53:51
    at MergeMapSubscriber.project (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\node_modules\@angular-devkit\schematics\src\rules\call.js:74:24)       
    at MergeMapSubscriber._tryNext (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\node_modules\rxjs\internal\operators\mergeMap.js:69:27)
    at MergeMapSubscriber._next (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\node_modules\rxjs\internal\operators\mergeMap.js:59:18)
    at MergeMapSubscriber.Subscriber.next (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\node_modules\rxjs\internal\Subscriber.js:66:18)
    at MergeMapSubscriber.notifyNext (G:\mis-cursos\quiz-api\node_modules\@nestjs\schematics\node_modules\rxjs\internal\operators\mergeMap.js:92:26)

Failed to execute command: "G:\mis-cursos\quiz-api\node_modules\@nestjs\cli\node_modules\.bin\schematics" @nestjs/schematics:module --name=core/database --no-dry-run --collection="@nestjs/schematics" --language="ts" --sourceRoot="src" --spec

Possible Solution

The work around is creating it manually.

Environment

Nest version: X.Y.Z

 
```bash
➜  quiz-api git:(master) nest info

 _   _             _      ___  _____  _____  _     _____ 
| \ | |           | |    |_  |/  ___|/  __ \| |   |_   _|
|  \| |  ___  ___ | |_     | |\ `--. | /  \/| |     | |  
| . ` | / _ \/ __|| __|    | | `--. \| |    | |     | |  
| |\  ||  __/\__ \| |_ /\__/ //\__/ /| \__/\| |_____| |_ 
\_| \_/ \___||___/ \__|\____/ \____/  \____/\_____/\___/ 


[System Information]
OS Version     : Windows 10
NodeJS Version : v12.16.2
YARN Version    : 1.22.4 

[Nest CLI]
Nest CLI Version : 7.1.5        

[Nest Platform Information]     
platform-express version : 7.0.9
mongoose version         : 6.4.0
common version           : 7.0.9
config version           : 0.4.0
core version             : 7.0.9
```

Others:

[tritoanst]

Another case: Your ‘app.module.ts’ (or ‘libName.module.ts’) edited.

@Module({
  imports: allModules,
  providers: [AppService],
})
export class AppModule {}

update with:

@Module({
  imports: [
    ...allModules,
  ],
  providers: [AppService],
})
export class AppModule {}

‘imports: …’ must end with: ‘]’

[ruslanguns]

This issue happened on upgrade, then after deleting node_modules directory it has dissapeared. Just noticed of that. Clossing the issue.