E0146: A template file's Go declares no struct

A .vuka.html file whose Go comes before its markup renders one struct, declared in that Go: the markup is the struct's view, its fields read by bare name. The file's Go declares none — only variables, functions, or types that aren't structs.

Wrong

<!-- page.vuka.html -->
<script lang="go">
package pages

var greeting = "hello"
</script>

<p>{greeting}</p>

Right

Declare the struct the markup renders:

<!-- page.vuka.html -->
<script lang="go">
package pages

type Page struct {
	Greeting string
}
</script>

<p>{Greeting}</p>