Fix "Import Defaults" selector not being initialized incorrectly

[jsjtxietian]

In ImportDefaultsEditor, when first call the function, last_selected can be the first one(Animation Library) and directly show the settings for "Animation Library", fix #80867

However, there is another option: show the <Select Importer> option, I decided to go with the first option but this one is ok too. Can change my code to impl this one.

[dalexeev]

However, there is another option: show the <Select Importer> option

In my opinion, <Select Importer> doesn't serve any purpose, we can remove it:

diff --git a/editor/import_defaults_editor.cpp b/editor/import_defaults_editor.cpp
index 98a9bfe9dc..a0ee2c2b66 100644
--- a/editor/import_defaults_editor.cpp
+++ b/editor/import_defaults_editor.cpp
@@ -169,17 +169,15 @@ void ImportDefaultsEditor::_importer_selected(int p_index) {
 
 void ImportDefaultsEditor::clear() {
 	String last_selected;
-	if (importers->get_selected() > 0) {
+	if (importers->get_selected() >= 0) {
 		last_selected = importers->get_item_text(importers->get_selected());
 	}
 
 	importers->clear();
 
-	importers->add_item("<" + TTR("Select Importer") + ">");
-	importers->set_item_disabled(0, true);
-
 	List<Ref<ResourceImporter>> importer_list;
 	ResourceFormatImporter::get_singleton()->get_importers(&importer_list);
+
 	Vector<String> names;
 	for (const Ref<ResourceImporter> &E : importer_list) {
 		String vn = E->get_visible_name();
@@ -190,8 +188,9 @@ void ImportDefaultsEditor::clear() {
 	for (int i = 0; i < names.size(); i++) {
 		importers->add_item(names[i]);
 
-		if (names[i] == last_selected) {
-			importers->select(i + 1);
+		if (names[i] == last_selected || (i == 0 && last_selected.is_empty())) {
+			importers->select(i);
+			_update_importer();
 		}
 	}
 }

[jsjtxietian]

In my opinion, <Select Importer> doesn't serve any purpose, we can remove it:

Agreed. The OptionButton itself is quite clear, thus maybe we don't need a placeholder there to tell the user to select one importer.

[dalexeev]

Looks good to me.

[YuriSizov]

The solution makes sense to me, but could you please amend your commit message to follow the preferred style of the project? Your first line needs concisely describe the change, so you can use the title of the PR for this purpose. You can keep the rest, just put it into commit's description instead.

[jsjtxietian]

Thank you for your help, I missed the commit message requirement mentioned in CONTRIBUTING.md, sorry for that!

[YuriSizov]

Thanks!