Fix bare else attribute emitted by every Button

[methodofaction]

What

button.templ used an if / else if chain inside the <button> element's attribute list to select the type attribute. The pinned templ version (v0.3.1001, per go.mod) mis-generates this pattern.

Replaced it with two independent, mutually exclusive conditions:

if btn.Type != "" {
    type={ btn.Type }
}
if btn.Type == "" && btn.Copy != "" {
    type="button"
}

Why

The generated code wrote a literal " else" into the markup outside any conditional, and demoted the else-branch to an independent if:

}                                    // end of `if btn.Type != ""`
WriteString(..., " else")            // ← unconditional
if btn.Copy != "" { ... }            // ← no longer mutually exclusive

Two consequences, both broader than a bare Type-only issue:

1. Every non-anchor Button emitted a bare else attribute — not just ones setting Type.
2. A Button with both Type and Copy set would emit two type attributes.

Browsers ignore the unknown else attribute and take the first type, so nothing broke at runtime — but the markup fails validation. This is pre-existing at main, not introduced by recent work.

Reviewer notes

Other else if sites are safe. 16 exist across .templ files. The authoritative check was grepping the ~255 committed *_templ.go files for the emitted literal — only button_templ.go matched. The rest are element-content position (checkbox, radio, toast, notification, filter, description_list), which templ compiles correctly; the select.templ hits are JavaScript inside a script block.

Why the comment is on the func doc, not next to the code. templ rejects // comments in attribute position outright. In element-content position it silently strips the comment text but emits the surrounding whitespace — an earlier attempt produced a stray WriteString(..., " ") before <button>. The doc-comment placement has zero output impact.

Regeneration. Do not use a globally-installed templ CLI if it is newer than the go.mod pin — it rewrites all *_templ.go files with templ.ResolveAttributeValue, which the pinned runtime lacks. This was regenerated with:

go run github.com/a-h/templ/cmd/templ@v0.3.1001 generate

The button_templ.go diff is the semantic change plus sequential index renumbering; no ResolveAttributeValue contamination. assets/popui.css is unchanged (no new utility classes).

Heads-up for anyone regenerating: templ generate reported updates=0 on runs where it did rewrite files. The counter is unreliable — verify against git status.

Verification

Rendered Buttons through the real component and asserted the opening tag:

Props	type=	bare else
Type: "submit"	submit	no
Type: "submit", Copy: "x"	submit (single attr)	no
Copy: "x"	button	no
neither	absent	no

go generate ./..., go build ./..., go vet ./..., go test ./... all clean.

🤖 Generated with Claude Code

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