Check Go templates for validity.

Using CheckedTemplate[T]:

t := template.Must(template.ParseFiles("index.tmpl"))
ct, err := templatecheck.NewChecked[IndexData](t)
if err != nil { ... }
// ct cannot have type errors.
data := IndexData{...}
...
// ct.Execute's second argument must be of type IndexData.
if err := ct.Execute(w, data); err != nil { ... }

Using CheckedTemplate[T] is recommended, but may require changes in how you write your templates and provide data to them. For example, if your template contains

{{.F}}

you can execute it with any value that has an F field or method. Two different calls to Template.Execute can pass in two different types, as long as each has F. With checked templates, you must fix a single type to use for execution.

Using the CheckXXX functions:

t := template.Must(template.ParseFiles("index.tmpl"))
if err := templatecheck.CheckHTML(t, homePage{}); err != nil {
    log.Fatal(err)
}

See the package documentation for details.