E2212 Package unit '%s' cannot appear in contains or uses clauses (Delphi)

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The unit named in the error is a package unit and as such cannot be included in your project. A possible cause of this error is that somehow a Delphi unit and a package unit have been given the same name. The compiler is finding the package unit on its search path before it can locate a same-named Delphi file. Packages cannot be included in a project by inclusion of the package unit in the uses clause.