Throw when parsedUrl is not provided

[timneutkens]

Fixes #990

[timneutkens]

cc @arunoda

[arunoda]

We should parse this. But we should throw if the user provided something other than a parsedUrl as the third argument.

[timneutkens]

@arunoda This throws in all cases where parsedUrl.query doesn't exist, which is fine since passing it through without true as second parameter will cause a re-parse otherwise, which is unneeded right? Or do you want to keep the url parsing when passing only req, res instead of req, res, parsedUrl?

[arunoda]

If the parsedUrl is undefined or null, I need to do parse the URL ourselves.

[timneutkens]

@arunoda fixed 🙌

[arunoda]

I think we don't need this line.

[arunoda]

Thanks @timneutkens
This looks great.