LibGUI+Everywhere: Use fallible Window::set_main_widget() everywhere :^)

Rip that bandaid off!

This does the following, in one big, awkward jump:
- Replace all uses of `set_main_widget<Foo>()` with the `try` version.
- Remove `set_main_widget<Foo>()`.
- Rename the `try` version to just be `set_main_widget` because it's now
  the only one.

The majority of places that call `set_main_widget<Foo>()` are inside
constructors, so this unfortunately gives us a big batch of new
`release_value_but_fixme_should_propagate_errors()` calls.

1 files changed, 6 insertions, 6 deletions

diff --git a/Userland/Games/Flood/SettingsDialog.cpp b/Userland/Games/Flood/SettingsDialog.cpp
index 2dcad063c8..873cab5ede 100644
--- a/Userland/Games/Flood/SettingsDialog.cpp
+++ b/Userland/Games/Flood/SettingsDialog.cpp
@@ -27,30 +27,30 @@ SettingsDialog::SettingsDialog(GUI::Window* parent, size_t board_rows, size_t bo
     set_icon(parent->icon());
     set_resizable(false);
 
-    auto& main_widget = set_main_widget<GUI::Widget>();
-    if (!main_widget.load_from_gml(settings_dialog_gml))
+    auto main_widget = set_main_widget<GUI::Widget>().release_value_but_fixme_should_propagate_errors();
+    if (!main_widget->load_from_gml(settings_dialog_gml))
         VERIFY_NOT_REACHED();
 
-    auto board_rows_spinbox = main_widget.find_descendant_of_type_named<GUI::SpinBox>("board_rows_spinbox");
+    auto board_rows_spinbox = main_widget->find_descendant_of_type_named<GUI::SpinBox>("board_rows_spinbox");
     board_rows_spinbox->set_value(m_board_rows);
 
     board_rows_spinbox->on_change = [&](auto value) {
         m_board_rows = value;
     };
 
-    auto board_columns_spinbox = main_widget.find_descendant_of_type_named<GUI::SpinBox>("board_columns_spinbox");
+    auto board_columns_spinbox = main_widget->find_descendant_of_type_named<GUI::SpinBox>("board_columns_spinbox");
     board_columns_spinbox->set_value(m_board_columns);
 
     board_columns_spinbox->on_change = [&](auto value) {
         m_board_columns = value;
     };
 
-    auto cancel_button = main_widget.find_descendant_of_type_named<GUI::Button>("cancel_button");
+    auto cancel_button = main_widget->find_descendant_of_type_named<GUI::Button>("cancel_button");
     cancel_button->on_click = [this](auto) {
         done(ExecResult::Cancel);
     };
 
-    auto ok_button = main_widget.find_descendant_of_type_named<GUI::Button>("ok_button");
+    auto ok_button = main_widget->find_descendant_of_type_named<GUI::Button>("ok_button");
     ok_button->on_click = [this](auto) {
         done(ExecResult::OK);
     };