Strange multiple export typing issue

[dkzlv]

Describe the bug
It is by no means a severe bug, but a very strange one still.
If you define multiple props on the same line and divide them with a comma, all the props except the first one would raise an error, that they are not defined despite their type, but only in the template, not in the script.

To Reproduce
So JS/TS allows you to define as many lets, consts and exports in one line. I usually use this to save some keystrokes.
Here's the code that works fine and generates no errors:

<script lang="ts">
  export let callback: () => void;
</script>

<button on:click={callback}>Click</button>

but this one raises an error in the template:

<script lang="ts">
  export let name: string, callback: () => void;

  let wrappedCallback: () => void;
  // No error! Hover shows right type for `callback`
  $: wrappedCallback = () => callback();
</script>

<!-- Error: Variable 'callback' is used before being assigned. -->
<button on:click={callback}>{name}</button>

It is very strange, since semantically it's the same as

export let name: string;
export let callback: () => void;

Should also say that this code is treated well by the IDE:

<script lang="ts">
  const check1 = 'qwerty',
    check2 = 'qwerty';
</script>

<p>{check1}, {check2}</p>

Expected behavior
It shouldn't raise any errors.

System (please complete the following information):
OS: Mac OS 10.15.3
IDE: VS Code
Plugin/Package: Svelte for VS Code (the new official one)

[dummdidumm]

Special case of #146, we need to adjust the regex to deal with this.

[dummdidumm]

Probably the better solution would be to return some kind of info from svelte2tsx about the props. This would remove the need for the regex and be more robust since svelte2tsx uses the typescript parser to get these infos.