Don't fail if there's no modules in combobox with unconfigured modules (EA-76203)

Confirmed reproduction steps:
1. Open Kotlin gradle project (or do the sync) - it will be considered unconfigured until synchronisation is finished
2. Click configure and see Choose Configuration popup
3. Wait sync is finished
4. Click proposed configurator in popup

As all projects are considered configured now, single module selection will be empty

idea/src/org/jetbrains/kotlin/idea/framework/ui/ChooseModulePanel.java

@@ -129,7 +129,10 @@ public class ChooseModulePanel {
     public List<Module> getModulesToConfigure() {
         if (allModulesRadioButton.isSelected()) return modules;
         if (allModulesWithKtRadioButton.isSelected()) return modulesWithKtFiles;
+
         String selectedItem = (String) singleModuleComboBox.getSelectedItem();
+        if (selectedItem == null) return Collections.emptyList();
+
         return Collections.singletonList(ModuleManager.getInstance(project).findModuleByName(selectedItem));
     }
 }