make resource resolving more graceful and fallback to original ctx.url

[thescientist13]

Related Issue

resolves #598

Summary of Changes

1. Fallback to original ctx.url instead of empty string when resolving

Thoughts

There might be a case to create a new issue or discussion to scope out some more capabilities for the dev server. In light of this issue, I'm wondering what other capabilities users may be expecting / need here that aren't, given the simplicity of the current implementation, for instance

• make sure cookies and headers are properly forward
• other methods like PUT, POST, DELETE, etc
• others?

Made a discussion - #607