Legacy client code not parsing __SAPPER_CSS_PLACEHOLDER

[silentworks]

It seems the legacy client code is not parsing the PLACEHOLDER text, this can be seen from the resulting output in the build directory.

Here is part of the output from build/client/client.******.js:

{
    pattern:/^\/about\/?$/,
    parts:[{
        component: {
            js:()=>import("./about.2dbe86cf.js"),
            css:["about.2dbe86cf.css","chunk.953bc4b7.css"]
        }
    }]
}

Here is part of the output from build/client/legacy/client.******.js:

{
    pattern:/^\/about\/?$/,
    parts:[{
        component:{
            js:function(){return import("./about.627078a3.js")},
            css:"__SAPPER_CSS_PLACEHOLDER:about.html__"
        }
    }]
}

This seem to be an issue at build time, it seems that build/client/client.******.js gets parsed by the extract_css function and written to file

sapper/src/core/create_compilers/extract_css.ts

Line 210 in 91f2c6e

fs.writeFileSync(`${dirs.dest}/client/${main}`, replaced);

, while build/client/legacy/client.******.js doesn't.

[silentworks]

I have a solution but it feels very much like a nasty hack.

In build.ts before line 83 I added client_result.to_json(manifest_data, dirs); and then inside of extract_css.ts after line 172 I added:

if (process.env.SAPPER_LEGACY_BUILD)
        main = `legacy/${main}`;

[Rich-Harris]

Released 0.20.4 with the fix — thank you