Hovering on a link with sveltekit:prefetch before JS loads throws an error on console

[pablo-abc]

Describe the bug
This might be related to the fix for #652 (in #654) which is working now. If the user has a slow connection and hovers on a link with the attribute sveltekit:prefetch before JS finishes loading, SvelteKit will throw multiple times the same error TypeError: can't access property "parse", this.router is null until it finishes loading. This does not seem to break anything else and the page keeps working.

Logs

Uncaught (in promise) TypeError: can't access property "parse", this.router is null
    prefetch http://localhost:3000/.svelte/dev/runtime/internal/start.js:482
    trigger_prefetch http://localhost:3000/.svelte/dev/runtime/internal/start.js:341
    mousemove_timeout http://localhost:3000/.svelte/dev/runtime/internal/start.js:352
    setTimeout handler*handle_mousemove http://localhost:3000/.svelte/dev/runtime/internal/start.js:351
    Renderer http://localhost:3000/.svelte/dev/runtime/internal/start.js:357
    start http://localhost:3000/.svelte/dev/runtime/internal/start.js:804
    <anonymous> http://localhost:3000/:138

To Reproduce
Set throttling in your browser to "Regular 2G" or something slow enough. Load the page and before the JS finishes loading, hover a link with sveltekit:prefetch. This should throw the above error in the console.

Expected behavior
No errors in console

Stacktraces
No stack trace

Information about your SvelteKit Installation:

 System:
    OS: macOS 11.2.3
    CPU: (8) x64 Apple M1
    Memory: 98.43 MB / 8.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 14.16.0 - ~/.volta/tools/image/node/14.16.0/bin/node
    Yarn: 1.22.10 - ~/.volta/tools/image/yarn/1.22.10/bin/yarn
    npm: 7.5.4 - ~/.volta/tools/image/npm/7.5.4/bin/npm
  Browsers:
    Chrome: 89.0.4389.90
    Firefox Developer Edition: 87.0
    Safari: 14.0.3
  npmPackages:
    @sveltejs/kit: 1.0.0-next.58 => 1.0.0-next.58
    svelte: ^3.0.0 => 3.35.0

• Tested in Firefox Developer Edition 87.0

• Adapter: static

Severity
Just annoying, doesn't seem to be breaking anything else at all (that I have noticed).

Additional context
N/A

[pablo-abc]

Fixed in #685

[pablo-abc]

I'm closing this seems it seems to have been fixed in #766 and I'm not having this issue anymore.