avm2: Fix getQualifiedClassName for null and undefined

core/src/avm2/globals/flash/utils.rs

@@ -193,10 +193,14 @@ pub fn get_qualified_class_name<'gc>(
     _this: Option<Object<'gc>>,
     args: &[Value<'gc>],
 ) -> Result<Value<'gc>, Error<'gc>> {
-    let obj = args
-        .get(0)
-        .unwrap_or(&Value::Undefined)
-        .coerce_to_object(activation)?;
+    // This is a native method, which enforces the argument count.
+    let val = args[0];
+    match val {
+        Value::Null => return Ok("null".into()),
+        Value::Undefined => return Ok("void".into()),
+        _ => {}
+    }
+    let obj = val.coerce_to_object(activation)?;
 
     let class = match obj.as_class_object() {
         Some(class) => class,

tests/tests/swfs/avm2/get_qualified_class_name/Test.as

@@ -20,4 +20,7 @@ trace(getQualifiedClassName(String));
 
 trace(getQualifiedClassName(new flash.utils.ByteArray()));
 
-trace(getQualifiedClassName(new String()));
+trace(getQualifiedClassName(new String()));
+
+trace(getQualifiedClassName(null));
+trace(getQualifiedClassName(undefined));

tests/tests/swfs/avm2/get_qualified_class_name/output.txt

@@ -5,4 +5,6 @@ com.very.long.namespace::example
 int
 String
 flash.utils::ByteArray
-String
+String
+null
+void