fixes #1409: internal server error with two slashes at the end of the URL

[syphar]

When iron finds a slash at the end of the route if will try to redirect if the route exists without the slash in the end.
This leads to an IronError which contains a normal permanent redirect as response.

This is no error for us, we can just return Ok(error.response) for these cases.

[jyn514]

Why will there still be a response if there's an error? Also, why does this also handle MovedPermanently? That seems like a change in behavior.

[syphar]

I'm not sure I follow.

In our own code we do redirects by returning an Ok(Response). Our code expects this and passes this through.

For this specific case (URL without slash at the end has a match, see the iron source), iron returns an IronError(Response).

Since for us the redirect is fine, and not an error, I want to convert this.

( of course I could be missing something)

[jyn514]

Ok, I think I see - we have our own error handler on top of iron's built-in error handlers. And our error handler expects to recognized every possible error, that's what the last or_else on line 197 is doing. Since iron has its own built-in error handlers, some of its errors (but not ours) will actually be valid HTTP responses that we can serve without changes.