Handles custom variables incorrectly

[KTibow]

Describe the bug

(This might be the wrong place but) when I use custom variables without a value, TS errors like Object literal may only specify known properties, and '"--type"' does not exist in type '{ type: "primary" | "tonal" | "text"; disabled?: boolean | undefined; }'.

Reproduction

<Component --var />

Expected behaviour

If --var="true" doesn't error, --var should either not error (as it evaluates into the same thing) or give a more clear error (if this isn't supposed to be allowed).

System Info

• OS: Fedora Workstation 38
• IDE: VS Code

Which package is the issue about?

svelte-check

Additional Information, eg. Screenshots

No response