if list has been collected, return nothing during collection

Author: qunaibit

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/cext/PythonCextListBuiltins.java

@@ -339,5 +339,11 @@ static long doGeneric(PList self, Object outItems,
             }
             return 0;
         }
+
+        @SuppressWarnings("unused")
+        @Specialization
+        static long doGeneric(PNone none, Object ignore) {
+            return 0;
+        }
     }
 }