fix(core): add missing catch handler for forward-ref provider resolution

[coti-z]

PR Checklist

• 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

• Bugfix

What is the current behavior?

Why is this a problem?

1. No .catch() handler → The error becomes an unhandled promise rejection
2. No settlementSignal.error() called → Other providers waiting on donePromise never receive the error
3. Waiting providers hang forever or receive undefined instead of a proper error

When a forwardRef provider fails to load in a non-static context (REQUEST/TRANSIENT scope), the error is silently swallowed. This happens because the promise chain in resolveComponentHost uses fire-and-forget pattern without a .catch() handler, causing unhandled promise rejections.

What is the new behavior?

Added a .catch() handler that propagates errors through settlementSignal.error(), matching the existing error handling pattern used elsewhere in the injector.

Does this PR introduce a breaking change?

• Yes
• No

Other information

• This fix follows the same error propagation pattern already used in loadInstance (lines 196-203).
• Added testcode

[coveralls]

Pull Request Test Coverage Report for Build 2097797b-97a8-412e-a64d-a1f81ae9b453

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 (+0.05%) to 89.759%

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Totals
Change from base Build 17dabc9f-0c10-4dd0-bc58-5458b80cef25:	0.05%
Covered Lines:	7441
Relevant Lines:	8290

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💛 - Coveralls

[kamilmysliwiec]

Out of curiosity: could you provide a minimum reproduction repository (that shows when the unhandled error occurs)?

[coti-z]

@kamilmysliwiec

Sure, I'll prepare a reproduction repository and mention you once it's ready.

[coti-z]

@kamilmysliwiec Here's the reproduction repository:

https://github.com/coti-z/unhandledRejection

Steps:

0. clone repository
1. npm install
2. npm run start:dev
3. curl http://localhost:3000/

Expected: BService throws → error propagates → request fails with 500
Actual: BService throws → AService receives undefined → request returns ok + UnhandledPromiseRejectionWarning

Let me know if you need anything else!

[kamilmysliwiec]

thanks @coti-z

[coti-z]

Glad I could help!