StructureMap threw an exception after some refactoring

StructureMap Exception Code: 202 No Default Instance defined for PluginFamily IDoSomething

Solved by removing duplicates from assembly scan:

ObjectFactory.Initialize(c =>
{
    c.Scan(s =>
    {
        s.TheCallingAssembly();
        // Already loaded with TheCallingAssembly above
        // s.AssemblyContainingType<SomethingImplementation>();
        s.ConnectImplementationsToTypesClosing(typeof(IDoSomething));
    });
});

Turned out the IDoSomething was mapped to 2 implementations (of the same type) and StructureMap could not decide which was the default.