Improve error messaging when using <#slot /> in template via embed_sface/1 macro

[harmon25]

Maybe it was because I was programming when I should have been in bed - but I got stumped by this. It took a bit of reflection to realize I needed to use {@inner_content} instead of default slot with embed_sface/1 and .sface templates.

Using <#slot /> here resulted in an ArgumentError like this:

(ArgumentError) errors were found at the given arguments:

  * 2nd argument: not a tuple

    :erlang.element(1, nil)
    (surface 0.11.0) lib/surface/compiler/eex_engine.ex:1214: Surface.Compiler.EExEngine.build_render_slot_context_expr/3
    (surface 0.11.0) lib/surface/compiler/eex_engine.ex:194: Surface.Compiler.EExEngine.to_expression/3
    (surface 0.11.0) lib/surface/compiler/eex_engine.ex:70: Surface.Compiler.EExEngine.generate_buffer/3
    (surface 0.11.0) lib/surface/compiler/eex_engine.ex:35: Surface.Compiler.EExEngine.translate/2
    (surface 0.11.0) expanding macro: Surface.embed_sface/1

Some better messaging would help a lot here - or maybe just a clear callout in the docs?

How to reproduce it

Updating the test/surface_test_embed_sface.sface to look like this can reproduce:

<div>embed_sface</div>
<#slot />

The behavior you expected

I expected <#slot /> to work, and the resulting ArgumentError was of little assistance.

Here is a suggestion:

error: Trying to use `<#slot />` in a deadview/template, use `{@innter_content}` instead.

Your Environment

Surface: v0.11.0
LiveView: v019.4
Elixir: v1.15.3