$ ./gopackages -mode=allsyntax "" "nonesuch"
Go package "_/home/adonovan/got/src/golang.org/x/tools": (has errors)
        has complete exported type info
        -: no Go files in /home/adonovan/got/src/golang.org/x/tools

Go package "nonesuch": (has errors)
        has complete exported type info
        -: cannot find package "nonesuch" in any of:
        /home/adonovan/goroot/src/nonesuch (from $GOROOT)
        /home/adonovan/go/src/nonesuch (from $GOPATH)

packages.Load("nonesuch") and Load("") both return a Package, presumably just as a place to hold errors. The package Name field is empty, which is a good clue that the package doesn't exist, and the Errors slice is non-empty. However, the Types field is non-nil and Complete(), which causes the gopackages diagnostic/example tool to report "has complete exported type info" for a package that doesn't exist.

The task of this issue is to clarify which fields can be relied upon in each error scenario and to improve the output and logic of the gopackages tool to reflect this.