Error messages needs improvement if package name is wrong

[gsalunke]

We identified a issue where the package name was used inside FASTN.ftd was wrong, but the error was shown for different package.

e.g.

-- fastn.dependency: fifthtry.github.io/fastn-typography
-- fastn.dependency: fastn-community.github.io/virgil-font-typography

in above case fastn-community.github.io/virgil-font-typography not exists, but fastn throws below error:

FastnCoreError(PackageError { message: "failed to parse P1Error(ParseError { message: \"library not found 1: fifthtry.github.io/fastn-typography\", doc_id: \"\", line_number: 0 })" })

Expected:

FastnCoreError(PackageError { message: "failed to parse P1Error(ParseError { message: \"library not found 1: fastn-community.github.io/virgil-font-typography\", doc_id: \"\", line_number: 0 })" })