You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: package.go
    path of file: ./repos/gqlgen/codegen/config
    
    the code of the file until where you have to start completion: package config

import (
	"fmt"
	"go/types"
	"path/filepath"
	"strings"

	"github.com/99designs/gqlgen/internal/code"
)

type PackageConfig struct {
	Filename      string          `yaml:"file
    
func (c *PackageConfig) Check() error {
	if strings.ContainsAny(c.Package, "./\\") {
		return fmt.Errorf("package should be the output package name only, do not include the output filename")
	}
	if c.Filename == "" {
		return fmt.Errorf("filename must be specified")
	}
	if !strings.HasSuffix(c.Filename, ".go") {
		return fmt.Errorf("filename should be path to a go source file")
	}

	c.Filename = abs(c.Filename)

	// If Package is not set, first attempt to load the package at the output dir. If that fails
	// fallback to just the base dir name of the output filename.
	if c.Package == "" {
		c.Package = code.NameForDir(c.Dir())
	}

	return nil
}