E0124: Code that can't run in the browser

A client-side expression (one reading a ui.State, kept current in the browser) is translated to JavaScript, and only state reads, literals and a small set of operators translate. A function call or another operator has to run on the server.

Wrong

<!-- tabs.vuka.html -->
<script lang="go">
type Tabs struct {
	tab ui.State[string]
}
</script>

<p>{strings.ToUpper(tab)}</p>

Right

<!-- tabs.vuka.html -->
<script lang="go">
type Tabs struct {
	tab ui.State[string]
}
</script>

<p>{tab}</p>   <!-- kept current in the browser; or compute the text on the server -->