RollupResult.to_json corrupts images

[benmccann]

Took me awhile to figure out that a method called to_json would be doing this until I opened it up:

sapper/src/core/create_compilers/RollupResult.ts

Line 92 in 6747275

// TODO extract_css has side-effects that don't belong

Something bad is happening here:

sapper/src/core/create_compilers/extract_css.ts

Line 227 in 6747275

fs.readdirSync(asset_dir).forEach(file => {

It appears to be overwriting my images. We should probably add a filter to make it operate only on .js files

[Conduitry]

Fixed in 0.27.14.