T11167_ambig.hs:10:13: error: [GHC-87543]
    Ambiguous occurrence ‘runContT’
    It could refer to
       either the field ‘runContT’ of record ‘ContT’,
              defined at T11167_ambig.hs:6:30
           or the field ‘runContT’ of record ‘ContT'’,
              defined at T11167_ambig.hs:7:32

T11167_ambig.hs:17:9: error: [GHC-87543]
    Ambiguous occurrence ‘runContT’
    It could refer to
       either the field ‘runContT’ of record ‘ContT’,
              defined at T11167_ambig.hs:6:30
           or the field ‘runContT’ of record ‘ContT'’,
              defined at T11167_ambig.hs:7:32