state file parsing errors should not assert (#3865)
state file parsing errors should not assert (#3865)

motivation: state parsing is a "legitimate" error that we handle gracefuly and should not assert on

changes: use StringError instead of InternalError when encountering invalid kind/type attribute
apple/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,abertelrud/swift-package-manager,abertelrud/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager