Check for PyAsyncGen when calling aiter

Author: sum12

vm/src/stdlib/builtins.rs

@@ -12,6 +12,7 @@ mod builtins {
     use crate::compile;
     use crate::{
         builtins::{
+            asyncgenerator::PyAsyncGen,
             enumerate::PyReverseSequenceIterator,
             function::{PyCellRef, PyFunctionRef},
             int::PyIntRef,
@@ -428,7 +429,11 @@ mod builtins {
 
     #[pyfunction]
     fn aiter(iter_target: PyObjectRef, vm: &VirtualMachine) -> PyResult {
-        vm.call_special_method(iter_target, "__aiter__", ())
+        if iter_target.payload_is::<PyAsyncGen>() {
+            vm.call_special_method(iter_target, "__aiter__", ())
+        } else {
+            Err(vm.new_type_error("wrong argument type".to_owned()))
+        }
     }
 
     #[pyfunction]