T14605.hs:14:13: error: [GHC-10283]
    • Couldn't match representation of type ‘x’ with that of ‘()’
        arising from a use of ‘coerce’
      ‘x’ is a rigid type variable bound by
        the type ()
        at T14605.hs:14:1-49
    • In the expression: coerce @(forall x. ()) @(forall x. x)
      In an equation for ‘duplicate’:
          duplicate = coerce @(forall x. ()) @(forall x. x)