TC does not introduce abstract constructor for syntax rules

[PaulKlint]

It seems that the type checker does not introduce abstract constructors for syntax rules with a constructor name.

import Exception;
import List;
import ParseTree;

syntax A = a: "a";

syntax As = as: A+ alist;

syntax C = c: A a "x" As as;

test bool tstA(){
    pt = [A] "a";
    return a() := pt ;
}

gives

error("Constructor name is not in scope",|rascal:///experiments/Compiler/Examples/Tst.rsc|(417,1,<23,11>,<23,12>))
error("Type of pattern could not be computed",|rascal:///experiments/Compiler/Examples/Tst.rsc|(417,3,<23,11>,<23,14>))
|rascal://experiments::Compiler::Rascal2muRascal::RascalModule|(2652,25,<80,12>,<80,37>): "Module contains errors!"

[mahills]

This now checks fine.