Problems reported:

parser/error_recovery/issue_39026_prime.crash:2:17: A method declaration needs an explicit list of parameters.
    co operator <{
                ^

beginCompilationUnit(class)
  beginMetadataStar(class)
  endMetadataStar(0)
  beginClassOrNamedMixinApplicationPrelude(class)
    handleIdentifier(A, classOrMixinDeclaration)
    handleNoTypeVariables({)
    beginClassDeclaration(class, null, A)
      handleNoType(A)
      handleClassExtends(null, 1)
      handleClassNoWithClause()
      handleClassOrMixinImplements(null, 0)
      handleClassHeader(class, class, null)
      beginClassOrMixinBody(DeclarationKind.Class, {)
        beginMetadataStar(co)
        endMetadataStar(0)
        beginMember()
          beginMethod(null, null, null, null, null, operator)
            handleIdentifier(co, typeReference)
            handleNoTypeArguments(operator)
            handleType(co, null)
            handleOperatorName(operator, <)
            handleNoTypeVariables({)
            handleRecoverableError(MissingMethodParameters, <, <)
            beginFormalParameters((, MemberKind.NonStaticMethod)
            endFormalParameters(0, (, ), MemberKind.NonStaticMethod)
            handleNoInitializers()
            handleAsyncModifier(null, null)
            beginBlockFunctionBody({)
            endBlockFunctionBody(0, {, })
          endClassMethod(null, co, (, null, })
        endMember()
      endClassOrMixinBody(DeclarationKind.Class, 1, {, })
    endClassDeclaration(class, })
  endTopLevelDeclaration()
endCompilationUnit(1, )