Non-inlined sourcemaps don't load

[ianstormtaylor]

Because the entrypoint server is really simple currently, and just serves sketch.js and sketch.js.map, if any of the imported packages in a sketch don't include their sourceContent inline in the sourcemap, they won't be able to be loaded by devtools.

In TypeScript a third-party package can make its source content inlined by setting…

{
    "sourceMap": true,
    "inlineSources": true,
}

…but many won't have done that.

Ideally either the server could serve all files (need to check if this is secure first though). Or the single sourcemap could get all of its source files's content inlined, and its JSON can be updated with the new source content strings before serving.