Describe the bug
When a function is used in a component props, its parameter cannot have a type. in the following code, x={(d: Point) => d.x} shows an error of:

Unexpected tokensvelte(parse-error)
Unexpected tokents(-1)

<Pancake.SvgLine
    data={[...points, { [x]: maxx, [field.key]: 0 }]}
    x={(d: Point) => d.x}
    y={(d) => d.y}
    let:d
    >
       <path class="data" {d} />
</Pancake.SvgLine>

Logs
Please include browser console and server logs around the time this bug occurred.

To Reproduce

1. create a brand new svelte ts project.
2. use a function in a prop and add a type to the parameter.
3. See the error

Version
svelte-preprocess version (Please check you can reproduce the issue with the latest release!)

latest 4.10.7