Method doesn't understand result return

[einar-hjortdal]

Describe the bug

In this function I am getting these compiler errors

providers.v:151:3: error: `errors.PeonyError` doesn't implement method `create` of interface `providers.BlobProvider`
  149 | fn (mut app App) get_blob_provider_instance() !&providers.BlobProvider {
  150 |     mut entry := app.providers.blob or {
  151 |         return errors.internal('No blob provider is installed', 'app.providers.blob is none')
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  152 |     }
  153 |
providers.v:151:3: error: `errors.PeonyError` doesn't implement method `delete` of interface `providers.BlobProvider`
  149 | fn (mut app App) get_blob_provider_instance() !&providers.BlobProvider {
  150 |     mut entry := app.providers.blob or {
  151 |         return errors.internal('No blob provider is installed', 'app.providers.blob is none')
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  152 |     }
  153 |
providers.v:156:4: error: `errors.PeonyError` doesn't implement method `create` of interface `providers.BlobProvider`
  154 |     instance := entry.instance or {
  155 |         new_instance := entry.factory() or {
  156 |             return errors.internal('Failed to get new blob provider instance', err.msg())
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  157 |         }
  158 |         return new_instance
providers.v:156:4: error: `errors.PeonyError` doesn't implement method `delete` of interface `providers.BlobProvider`
  154 |     instance := entry.instance or {
  155 |         new_instance := entry.factory() or {
  156 |             return errors.internal('Failed to get new blob provider instance', err.msg())
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  157 |         }
  158 |         return new_instance

errors.PeonyError implements IError, but this function thinks I am returning providers.BlobProvider instead.

Reproduction Steps

git clone https://github.com/einar-hjortdal/peony.git
cd peony
git checkout c352965f3b2b446ab0b25444792b6aaccf72237d
v install
v run tests/peony_test.v 

Expected Behavior

Other errors, not this one.

Current Behavior

error: errors.PeonyError doesn't implement method delete of interface providers.BlobProvider

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.5.2 667fbb9

Environment details (OS name and version, etc.)

V full version	V 0.5.2 58f1857.667fbb9
OS	linux, "openmamba release 2026.7 for x86_64 (rolling)"
Processor	8 cpus, 64bit, little endian, Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
Memory	3.47GB/31.17GB
V executable	/home/einar/.local/lib64/v/v
V last modified time	2026-08-03 08:35:56
V home dir	OK, value: /home/einar/.local/lib64/v
VMODULES	OK, value: /home/einar/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /home/einar/Documents/projects/vlang/active/peony
Git version	git version 2.55.0
V git status	weekly.2026.03-2776-g667fbb9e
.git/config present	true
cc version	cc (GCC) 16.1.0
gcc version	gcc (GCC) 16.1.0
clang version	N/A
tcc version	tcc version 0.9.28rc 2025-02-13 HEAD@f8bd136d (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 696c1d84
emcc version	N/A
glibc version	ldd (GNU libc) 2.44

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[einar-hjortdal]

I am currently unable to create a minimal replication

module main

struct ReproError {
	s string
}

// IError
fn (e ReproError) msg() string {
	return e.s
}

fn (e ReproError) code() int {
	return 0
}

fn repro_error(msg string) ReproError {
	return ReproError{
		s: msg
	}
}

interface Something {
	create() !
}

struct Provider {}

fn new_provider() !&Provider {
	return repro_error('failed')
}

fn (p Provider) create() ! {}

fn main() {
	_ := new_provider()!
}

This one compiles as expected

[einar-hjortdal]

minimal repro:

module main

pub struct ReproError {
	s string
}

// IError
fn (e ReproError) msg() string {
	return e.s
}

fn (e ReproError) code() int {
	return 0
}

pub fn repro_error(msg string) ReproError {
	return ReproError{
		s: msg
	}
}

pub interface Something {
	create() !
}

struct SomethingImpl {}

fn (p SomethingImpl) create() ! {}

fn new_something_instance() !&SomethingImpl {
	return &SomethingImpl{}
}

struct App {
mut:
	something ?&Something
}

fn (mut app App) get_something() !&Something {
	mut something := app.something or {
		return repro_error('no instance of something')
		// new_something := new_something_instance()!
		// new_something
	}

	return something
}

fn main() {
	mut app := &App{}

	_ := app.get_something()!
}