returns "recovered" for getConstructor name on error productions such…

… that "is" operator and others work on error trees. This does reserve the constructor name "recovered" for use in error versions..

src/org/rascalmpl/interpreter/result/ConcreteSyntaxResult.java

@@ -55,6 +55,7 @@ public Result<IBool> is(Name name) {
 				return ResultFactory.bool(Names.name(name).equals(consName), ctx);
 			}
 		}
+
 		return ResultFactory.bool(false, ctx);
 	}
 

src/org/rascalmpl/values/parsetrees/ProductionAdapter.java

@@ -38,10 +38,15 @@ private ProductionAdapter() {
 	 * @return a constructor name if present or null otherwise
 	 */
 	public static String getConstructorName(IConstructor tree) {
-		IConstructor def = getDefined(tree);
+		if (isDefault(tree)) {
+			IConstructor def = getDefined(tree);
 
-		if (SymbolAdapter.isLabel(def)) {
-			return SymbolAdapter.getLabel(def);
+			if (SymbolAdapter.isLabel(def)) {
+				return SymbolAdapter.getLabel(def);
+			}
+		}
+		else if (isError(tree)) {
+			return "recovered";
 		}
 
 		return null;