findInheritanceChain, ensure-condition

[michaellilltokiwa]

test is

  Some_Ref ref is
    say "hello"

  a : choice i32 String, Some_Ref is

  b a := 2

error 1: java.lang.Error: ensure-condition failed: AbstractFeature.java:1533 "(this == Types.f_ERROR || ancestor == Types.f_ERROR || Errors.any() || result != null);"
        at dev.flang.util.ANY.ensure(ANY.java:293)
        at dev.flang.ast.AbstractFeature.findInheritanceChain(AbstractFeature.java:1533)
        at dev.flang.air.Clazz.findRedefinition(Clazz.java:993)
        at dev.flang.air.Clazz.lookup(Clazz.java:1205)
        at dev.flang.air.Clazzes.findClazzes(Clazzes.java:815)
        at dev.flang.air.Clazz$EV.action(Clazz.java:138)
        at dev.flang.ast.Expr.visitExpressions(Expr.java:330)
        at dev.flang.ast.AbstractCall.visitExpressions(AbstractCall.java:98)
        at dev.flang.ast.AbstractFeature.visitExpressions(AbstractFeature.java:1625)
        at dev.flang.air.Clazz.inspectCode(Clazz.java:1514)
        at dev.flang.air.Clazz.findAllClasses(Clazz.java:1558)
        at dev.flang.air.Clazzes.findAllClasses(Clazzes.java:469)
        at dev.flang.fuir.AirFUIR.<init>(AirFUIR.java:165)
        at dev.flang.opt.Optimizer.fuir(Optimizer.java:79)
        at dev.flang.tools.Fuzion$Backend.processFrontEnd(Fuzion.java:507)
        at dev.flang.tools.Fuzion.lambda$parseArgsForBackend$4(Fuzion.java:1072)
        at dev.flang.tools.Tool.lambda$run$0(Tool.java:142)
        at dev.flang.util.Errors.runAndExit(Errors.java:895)
        at dev.flang.tools.Tool.run(Tool.java:142)
        at dev.flang.tools.Fuzion.main(Fuzion.java:627)


*** fatal errors encountered, stopping.
one error.