Linter Rule: Disallow bare state reads in silent tags

Rule: herb-state-no-silent-reads

Description

Disallows a silent ERB tag whose whole content is a bare read of a declared state, like <% draft %>.

Rationale

A silent tag evaluates its expression and throws the result away, and a state read has no side effect to keep. The line renders nothing, changes nothing, and looks like it does one or the other. The author usually meant <%= draft %> to show the value, or wanted to change the state, which happens through data-herb-set and its siblings in markup and through state.set in app code, never through ERB.

The generic erb-no-unused-expressions rule steps aside for declared states inside their scope, so one mistake draws this one state-aware offense.

Examples

✅ Good

<%# herb:slots client %>
<%# herb:state (draft: "") %>

<p><%= draft %></p>
<button data-herb-set="draft=">Clear</button>

🚫 Bad

<%# herb:slots client %>
<%# herb:state (draft: "") %>

<% draft %>
`<% draft %>` reads the state `draft` and discards the value, so it renders nothing and changes nothing. Show it with `<%= draft %>`, or write it from markup with `data-herb-set`. (herb-state-no-silent-reads)
<input value="<%= draft %>">

References

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