Fix accidental creation of rigid variables when type-checking mixed record types when a type alias is given
Fix accidental creation of rigid variables when type-checking mixed record types when a type alias is given

Fixes the issue raised by Alexander

mgold/Elm,deadfoxygrandpa/Elm,5outh/Elm,JoeyEremondi/elm-pattern-effects,laszlopandy/elm-compiler,pairyo/elm-compiler,Axure/elm-compiler