LibGfx+Userland: Make Gfx::SystemTheme propagate errors

This patch introduces error propagation to Gfx::SystemTheme to remove
instances of release_value_but_fixme_should_propagate_errors().

Userland applications that have been affected by this change have been
updated to utilise this propagation and as a result 4 such instances of
the aforementioned method have been removed.

3 files changed, 8 insertions, 7 deletions

diff --git a/Userland/Services/Taskbar/main.cpp b/Userland/Services/Taskbar/main.cpp
index 1dede77962..ed57f2ccc2 100644
--- a/Userland/Services/Taskbar/main.cpp
+++ b/Userland/Services/Taskbar/main.cpp
@@ -227,7 +227,7 @@ ErrorOr<NonnullRefPtr<GUI::Menu>> build_system_menu(GUI::Window& window)
     g_themes_menu = &system_menu->add_submenu("&Themes");
     g_themes_menu->set_icon(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/themes.png"sv).release_value_but_fixme_should_propagate_errors());
 
-    g_themes = Gfx::list_installed_system_themes();
+    g_themes = TRY(Gfx::list_installed_system_themes());
     auto current_theme_name = GUI::ConnectionToWindowServer::the().get_system_theme();
 
     {
diff --git a/Userland/Services/WindowServer/WindowManager.cpp b/Userland/Services/WindowServer/WindowManager.cpp
index 128e8d0f98..95fd787e4e 100644
--- a/Userland/Services/WindowServer/WindowManager.cpp
+++ b/Userland/Services/WindowServer/WindowManager.cpp
@@ -2064,9 +2064,12 @@ void WindowManager::invalidate_after_theme_or_font_change()
 
 bool WindowManager::update_theme(DeprecatedString theme_path, DeprecatedString theme_name, bool keep_desktop_background)
 {
-    auto new_theme = Gfx::load_system_theme(theme_path);
-    if (!new_theme.is_valid())
+    auto error_or_new_theme = Gfx::load_system_theme(theme_path);
+    if (error_or_new_theme.is_error()) {
+        dbgln("WindowManager: Updating theme failed, error {}", error_or_new_theme.error());
         return false;
+    }
+    auto new_theme = error_or_new_theme.release_value();
     m_theme_overridden = false;
     Gfx::set_system_theme(new_theme);
     m_palette = Gfx::PaletteImpl::create_with_anonymous_buffer(new_theme);
@@ -2101,8 +2104,7 @@ void WindowManager::clear_theme_override()
 {
     m_theme_overridden = false;
     auto previous_theme_name = m_config->read_entry("Theme", "Name");
-    auto previous_theme = Gfx::load_system_theme(DeprecatedString::formatted("/res/themes/{}.ini", previous_theme_name));
-    VERIFY(previous_theme.is_valid());
+    auto previous_theme = MUST(Gfx::load_system_theme(DeprecatedString::formatted("/res/themes/{}.ini", previous_theme_name)));
     Gfx::set_system_theme(previous_theme);
     m_palette = Gfx::PaletteImpl::create_with_anonymous_buffer(previous_theme);
     invalidate_after_theme_or_font_change();
diff --git a/Userland/Services/WindowServer/main.cpp b/Userland/Services/WindowServer/main.cpp
index 06a9a9375a..2238e32ce8 100644
--- a/Userland/Services/WindowServer/main.cpp
+++ b/Userland/Services/WindowServer/main.cpp
@@ -44,8 +44,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
     auto wm_config = TRY(Core::ConfigFile::open("/etc/WindowServer.ini"));
     auto theme_name = wm_config->read_entry("Theme", "Name", "Default");
 
-    auto theme = Gfx::load_system_theme(DeprecatedString::formatted("/res/themes/{}.ini", theme_name));
-    VERIFY(theme.is_valid());
+    auto theme = TRY(Gfx::load_system_theme(DeprecatedString::formatted("/res/themes/{}.ini", theme_name)));
     Gfx::set_system_theme(theme);
     auto palette = Gfx::PaletteImpl::create_with_anonymous_buffer(theme);