do not throw RErrors created during parsing through PolyglotEngine

com.oracle.truffle.r.engine/src/com/oracle/truffle/r/engine/TruffleRLanguage.java

@@ -134,11 +134,18 @@ public final class TruffleRLanguage extends TruffleLanguage<RContext> {
                     public Object call(Object... arguments) {
                         try {
                             throw e.throwAsRError();
-                        } catch (@SuppressWarnings("hiding") RError e) {
+                        } catch (RError e2) {
                             return null;
                         }
                     }
                 };
+            } catch (RError e) {
+                return new CallTarget() {
+                    @Override
+                    public Object call(Object... arguments) {
+                        return null;
+                    }
+                };
             }
         }
     }