Turn off source maps by default

[arunoda]

Actually, here's my key points for this:

• Babel errors (with HMR) works without source maps properly
• Stack traces don't know how to handle source maps
• This slows down the app by 4X or more (This is a big deal)
• One can turn on source maps with our custom next.config.js

[timneutkens]

The only place it is needed is styled-jsx. To show styling locations. I'm not sure if this is related to webpack's sourcemaps though.

[arunoda]

I think styled-jsx babel plugin does that. (not webpack)

[arunoda]

Another idea, for the dev build we can use https://github.com/babel/babel-preset-env to not to transpile a lot. So, we don't really need source maps.

[aesopwolf]

@arunoda do you have an example of how to turn on source maps with next.config.js?

[arunoda]

@aesopwolf check this: #918 (comment)

[arunoda]

Even source-maps add some(considerable) overhead. It's pretty useful when debugging the code.
So, I'll close this issue.