Cannot implement interfaces in a module

[mistermoe]

Repro

1. replace the contents of examples/go/echo/echo.go with the following

// This is the echo module.
package echo

import (
	"context"
	"fmt"

	"ftl/time"

	"github.com/TBD54566975/ftl/go-runtime/ftl"
)

var defaultName = ftl.Config[string]("default")

type SomeInterface interface {
	A() string
}

type Thing struct{}

func (t Thing) A() string {
	return "thing"
}

// An echo request.
type EchoRequest struct {
	Name ftl.Option[string] `json:"name"`
}

type EchoResponse struct {
	Message string `json:"message"`
}

// Echo returns a greeting with the current time.
//
//ftl:verb
func Echo(ctx context.Context, req EchoRequest) (EchoResponse, error) {
	tresp, err := ftl.Call(ctx, time.Time, time.TimeRequest{})
	if err != nil {
		return EchoResponse{}, err
	}

	return EchoResponse{Message: fmt.Sprintf("Hello, %s!!! It is %s!", req.Name.Default(defaultName.Get(ctx)), tresp.Time)}, nil
}

2. run ftl dev --recreate ./examples/go

Output

❯ ftl dev --recreate ./examples/go
info: Starting FTL with 1 controller(s)
info:controller0: Web console available at: http://localhost:8892
info:controller0: HTTP ingress server listening on: http://localhost:8891
info: FTL startup command ⚡️
info:time: Building module
info:time: Deploying module
info:echo: Building module
info:controller0: Deployed dpl-time-5cblpvv3s76l8ufx
info: Modules waiting to build: echo
error: initial deploy failed: /path/to/ftl/examples/go/echo/echo.go:19:1-20: could not find enum called SomeInterface

Expected Behavior

error: initial deploy failed: /ftl/examples/go/echo/echo.go:19:1-20: could not find enum called SomeInterface