DOC Remove incorrect getattr limitation from docs (#899)

docs/type_conversions.md

@@ -85,31 +85,6 @@ to make this more complete):
 | `x == y`       | `x == y`        |
 | `x.typeof`     | `typeof x`      |
 
-One important difference between Python objects and Javascript objects is that
-if you access a missing member in Python, an exception is raised. In Javascript,
-it returns `undefined`. Since we can't make any assumptions about whether the
-Javascript member is missing or simply set to `undefined`, Python mirrors the
-Javascript behavior. For example:
-
-```javascript
-// Javascript
-class Point {
-  constructor(x, y) {
-    this.x = x;
-    this.y = y;
-  }
-}
-point = new Point(42, 43))
-```
-
-```python
-# python
-from js import point
-assert point.y == 43
-del point.y
-assert point.y is None
-```
-
 ### Python from Javascript
 
 When passing a Python object to Javascript, the Javascript [Proxy

src/tests/test_typeconversions.py

@@ -1,5 +1,6 @@
 # See also test_pyproxy, test_jsproxy, and test_python.
 import pytest
+from selenium.common.exceptions import WebDriverException
 
 
 def test_python2js(selenium):
@@ -240,3 +241,33 @@ def test_error_from_js(selenium):
 def test_error_from_python(selenium):
     selenium.run("err = Exception('hello there?');")
     assert_py_to_js_to_py(selenium, "err")
+
+
+def test_jsproxy_attribute_error(selenium):
+    selenium.run_js(
+        """
+        class Point {
+            constructor(x, y) {
+                this.x = x;
+                this.y = y;
+            }
+        }
+        window.point = new Point(42, 43)
+        """
+    )
+    selenium.run(
+        """
+        from js import point
+        assert point.y == 43
+        """
+    )
+
+    msg = "AttributeError: z"
+    with pytest.raises(WebDriverException, match=msg):
+        selenium.run("point.z")
+
+    selenium.run("del point.y")
+    msg = "AttributeError: y"
+    with pytest.raises(WebDriverException, match=msg):
+        selenium.run("point.y")
+    assert selenium.run_js("return point.y;") is None