Go template missingkey option always return error

So the question seems to have been asked a couple of times before, but none of the previous answers worked for me, I go from errors to errors to no results.

So as I am most certainly missing something that I don't see I would like for some help:

res, err := os.Create(strings.Replace(f, ".tmpl", "", -1))
if err != nil {
  log.Fatal(err)
}

t, err := template.ParseFiles(f)
if err != nil {
  log.Fatal(err)
}

removes = append(removes, res.Name())

config := make(map[string]string)
for _, v := range vars {
  config[v] = os.Getenv(v)
}

err = t.Execute(res, config)
if err != nil {
  log.Fatal(err)
}

res.Close()

So to explain what I am doing, I'm passing a string to a file (path/file) that has a yaml.tmpl extension. The result file should be yaml so I remove the last part to generate the result file name.

I then parse the file with go template and then I execute with a configmap that I generate.

This is working fine like this but I would like to add: .Option("missingkey=error") to have it generate an error in case I don't give a value from the configmap to a variable in the template.

So I tried to add the options in the template parse file like this:

t, err := template.New("test").Option("missingkey=error").ParseFiles(f)

But I can't use template Exectute and have to use template ExecuteTemplate but with those I get:
template: no template "test" associated with template "test" or template: test: "test" is an incomplete or empty template

In the rare cases I don't get an error, it just ignore the option like if I do this:

err = t.Option("missingkey=error").Execute(res, config)

Does anyone has an idea of what I'm doing wrong?

EDIT

I updated the code with the answer of Cerise Limon and here is the playground: playground

Currently that playground just ignore errors and do the template even if the config passed is empty and there is no or condition in the template.

The ParseFiles method documentation says:

> Since the templates created by ParseFiles are named by the base names of the argument files, t should usually have the name of one of the (base) names of the files.

Use filepath.Base to get the base name of the file. Use that name as the name of the template:

 t, err := template.New(filepath.Base(f)).Option("missingkey=error").ParseFiles(f)

Run an example on the Playground.