Embedded playground with login

The feature of embedding the playground seems broken.
https://svelte.dev/playground/embed which translates to https://svelte.dev/playground/hello-world/embed?version=5.0.0-next.272 (I've tried to manually change the version to 5.1.3 which is the current version on the svelte.dev site and is the same) doesn't work and freezes on loading Svelte Compiler
Browser console gives this error for Editor.DgIedeOC.js:426

Uncaught (in promise) Error: Workspace must have at least one file
    at Ck.set (Editor.DgIedeOC.js:426:8826)
    at Ck.reset (Editor.DgIedeOC.js:426:8508)
    at Proxy.x (config.BSQVWH8N.js:68:6165)
    at 9.JGmp0oYm.js:1:1331
    at entry.D0hSBSpY.js:1:13001
    at Array.forEach (<anonymous>)
    at st (entry.D0hSBSpY.js:1:12990)
    at fn (entry.D0hSBSpY.js:1:26819)
    at async Module.yn (entry.D0hSBSpY.js:1:11374)

Reproduce the failure at https://svelte.dev/playground/hello-world/embed?version=5.0.0-next.272 and inspect the console stack trace, especially Editor.DgIedeOC.js:426 and config.BSQVWH8N.js:68. Trace why the embedded workspace has no files; done means the playground loads past “loading Svelte Compiler” without the workspace error.