fix(core): when using forward references on exports array

[micalevisk]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

the following code triggers the error because of the forwardRef on exports array

import { Module, forwardRef } from '@nestjs/common';

@Module({})
export class FooModule {}

@Module({
  imports: [
    forwardRef(() => FooModule),
  ],
  exports: [forwardRef(() => FooModule)],
})
export class AppModule {}

Which breaks the ConditionModule from @nestjs/config when we use a forward reference.

Do note that the same error happens when we supply a promise to exports:

but I didn't address this error in this PR because I'm not sure about the error handling for rejected promises and about the right place to resolve such promise.

What is the new behavior?

we can now use forwardRef on exports, as its type definition tell us so.

I also made a tiny change to the issue template of bug reports. It will look like this:

Does this PR introduce a breaking change?

• Yes
• No

Other information

I guess such usage was supposed to be supported since this commit: 0fcdf4e

[coveralls]

Pull Request Test Coverage Report for Build ae758b3c-61b4-4091-ac37-30a901dce476

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.001%) to 92.208%

---

Totals
Change from base Build 0f9b0016-1853-4775-8f4d-a4d89fc35f0f:	0.001%
Covered Lines:	6745
Relevant Lines:	7315

---

💛 - Coveralls

[kamilmysliwiec]

lgtm