Code review comment for lp:~zorba-coders/zorba/bug-867376

I think actually there are some error conditions that we're not catching currently. For instance, the following input in serialize-direct-uri.xq:

{ "scheme" : "file", "path" : "d:/a/b/c" }

is a non-opaque URI because it has a path, rather than an opaque-part. But it produces the output:

file:d:/a/b/c

which is an opaque URI. I believe that the input is illegal, because a non-opaque URI with a scheme MUST have a path section that begins with a / character. So the above input should actually raise an error.