Set `currentScript` to `null` for module scripts

I misunderstood the test case when I worked on #23545. That test case is
actually not related to dynamic import; instead, the reason why it
crashes is, `currentScript` should be updated to `null`.

components/script/dom/htmlscriptelement.rs

@@ -756,14 +756,18 @@ impl HTMLScriptElement {
         let document = document_from_node(self);
         let old_script = document.GetCurrentScript();
 
+        match script.type_ {
+            ScriptType::Classic => document.set_current_script(Some(self)),
+            ScriptType::Module => document.set_current_script(None),
+        }
+
         match script.type_ {
             ScriptType::Classic => {
-                document.set_current_script(Some(self));
                 self.run_a_classic_script(&script);
                 document.set_current_script(old_script.as_deref());
             },
             ScriptType::Module => {
-                assert!(old_script.is_none());
+                assert!(document.GetCurrentScript().is_none());
                 self.run_a_module_script(&script, false);
             },
         }