Duplicate error message on package resolved (#3257)
Duplicate error message on package resolved (#3257)

motivation: fix a bug where in some cases a duplicate error message is printed

changes: only try to load the graph if the previous operation succeeded
abertelrud/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager