Sass source map for dev

[alicialics]

#5707

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[bugzpodder]

I tested this and it looks great. Thank you!

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[ianschmitz]

Shouldn't style-loader have sourceMap enabled as well?

https://github.com/postcss/postcss-loader#sourcemap
https://github.com/webpack-contrib/style-loader#options

[bugzpodder]

cc @Fabianopb
According to https://github.com/webpack-contrib/sass-loader#source-maps it didn't say it was needed on style-loader. this set of changes on dev is consistent with the config on prod, I would imagine that it should be added two both configs if deemed necessary.

[Fabianopb]

It's been many months, but I had in my mind that it wasn't necessary to enable sourceMap in style-loader because I remember seeing this documentation that @bugzpodder referenced here.

But, not sure now, as @ianschmitz noticed from the style-loader docs, it seems to be required.

Apparently we have conflicting information, should we ask someone from webpack-contrib to confirm?

[stale]

This pull request has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

[stale]

This pull request has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

[bugzpodder]

@zhuoli99 Can you rebase this diff with the latest webpack config changes? Thanks!