improve the error message for #4659; closes #4659
improve the error message for #4659; closes #4659

russpowers/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,russpowers/Nim,russpowers/Nim,russpowers/Nim,russpowers/Nim,russpowers/Nim,russpowers/Nim,dom96/Nim