[WIP] Fix segfault in waybar::modules::sway::Language::set_current_layout

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Segfault in waybar::modules::sway::Language::set_current_layout</issue_title>
<issue_description>I've got the following segfault in Waybar 0.14.0:

Core was generated by `/nix/store/g2r7rc3p1d6m36d5y1ja53rkranfgxwr-waybar-0.14.0/bin/waybar -b bar-0'.
Program terminated with signal SIGSEGV, Segmentation fault.
Alexays/Waybar#0  0x00007f72f8702d18 in g_source_set_name_full (source=0x7f72300061a0, name=0x7f72f93b43f8 "[gtk+] gdk_frame_clock_paint_idle", is_static=0) at ../glib/gmain.c:2202
2202	 if (!source->priv->static_name)
[Current thread is 1 (Thread 0x7f725e7fc6c0 (LWP 35434))]

(gdb) list
2197	 /* setting back to NULL is allowed, just because it's
2198	  * weird if get_name can return NULL but you can't
2199	  * set that.
2200	  */
2201	
2202	 if (!source->priv->static_name)
2203	   g_free (source->name);
2204	
2205	 if (is_static)
2206	   source->name = (char *)name;
(gdb) bt full
Alexays/Waybar#0  0x00007fe245702d18 in g_source_set_name_full (source=0x7fe188006400, name=0x7fe2463b43f8 "[gtk+] gdk_frame_clock_paint_idle", is_static=0) at ../glib/gmain.c:2202
        context = <optimized out>
        _g_boolean_var_89 = <optimized out>
        _g_boolean_var_90 = <optimized out>
        gaig_temp = <optimized out>
Alexays/Waybar#1  0x00007fe245d10de9 in gtk_widget_add_tick_callback (widget=0x55bd49ab9f80 [gtkmm__GtkWindow], callback=callback@entry=0x7fe245afb960 <gtk_css_widget_node_queue_callback>, user_data=user_data@entry=0x55bd49a3f7f0, notify=notify@entry=0x0) at ../gtk/gtkwidget.c:5368
        priv = 0x55bd49ab9e90
        info = <optimized out>
        frame_clock = 0x55bd49d9d060 [GdkFrameClockIdle]
Alexays/Waybar#2  0x00007fe245afb946 in gtk_css_widget_node_queue_validate (node=0x55bd49a3f7f0 [GtkCssWidgetNode]) at ../gtk/gtkcsswidgetnode.c:95
        widget_node = 0x55bd49a3f7f0 [GtkCssWidgetNode]
Alexays/Waybar#3  0x00007fe245ad83cb in gtk_css_node_invalidate_style (cssnode=0x55bd49b58f40 [GtkCssWidgetNode]) at ../gtk/gtkcssnode.c:727
Alexays/Waybar#4  gtk_css_node_invalidate (cssnode=cssnode@entry=0x55bd49b58f40 [GtkCssWidgetNode], change=<optimized out>, change@entry=1) at ../gtk/gtkcssnode.c:1372
Alexays/Waybar#5  0x00007fe245ad8ad5 in gtk_css_node_remove_class (cssnode=0x55bd49b58f40 [GtkCssWidgetNode], style_class=<optimized out>) at ../gtk/gtkcssnode.c:1254
Alexays/Waybar#6  0x000055bd41f1303a in waybar::modules::sway::Language::set_current_layout (this=this@entry=0x55bd49c632a0, current_layout="Russian") at ../src/modules/sway/language.cpp:128
Alexays/Waybar#7  0x000055bd41f160bb in waybar::modules::sway::Language::onEvent (this=0x55bd49c632a0, res=...) at ../src/modules/sway/language.cpp:89
        lock = {_M_device = <optimized out>}
        payload = {static minLargestInt = -9223372036854775808, static maxLargestInt = 9223372036854775807, static maxLargestUInt = 18446744073709551615, static minInt = -2147483648, static maxInt = 2147483647, static maxUInt = 4294967295, static minInt64 = -9223372036854775808, static maxInt64 = 9223372036854775807, static maxUInt64 = 18446744073709551615, static defaultRealPrecision = 17, static maxUInt64AsDouble = 1.8446744073709552e+19, value_ = {int_ = 140606626094832, uint_ = 140606626094832, real_ = 6.9468903531101842e-310, bool_ = 240, string_ = 0x7fe188005ef0 "\205\343\030v\346\177", map_ = 0x7fe188005ef0}, bits_ = {value_type_ = 7, allocated_ = 0}, comments_ = {ptr_ = std::unique_ptr<struct std::array<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, 3>> = {get() = 0x0}}, start_ = 35, limit_ = 295}
Alexays/Waybar#8  0x000055bd41f06bfe in sigc::internal::signal_emit1<void, waybar::modules::sway::Ipc::ipc_response const&, sigc::nil>::emit (impl=0x55bd49b59c10, _A_a1=...) at /nix/store/blx56cg23z09bihhxlv4xsa3zb58irzp-libsigc++-2.12.1-dev/include/sigc++-2.0/sigc++/signal.h:1041
        slot = @0x55bd49b59c50: {<sigc::functor_base> = {<No data fields>}, rep_ = 0x55bd49b59b80, blocked_ = false}
        exec = {sig_ = 0x55bd49b59c10}
        slots = Python Exception <class 'gdb.error'>: value has been optimized out
{slots_ = <optimized out>, placeholder = }
Alexays/Waybar#9  0x000055bd41f06af7 in sigc::signal1<void, waybar::modules::sway::Ipc::ipc_response const&, sigc::nil>::emit (this=0x55bd49c635c8, _A_a1=...) at /nix/store/blx56cg23z09bihhxlv4xsa3zb58irzp-libsigc++-2.12.1-dev/include/sigc++-2.0/sigc++/signal.h:2961
Alexays/Waybar#10 waybar::modules::sway::Ipc::handleEvent (this=0x55bd49c635c8) at ../src/modules/sway/ipc/client.cpp:154
        res = {size = 297, type = 2147483669, payload = "{ \"change\": \"xkb_layout\", \"input\": { \"identifier\": \"0:0:wlr_virtual_keyboard_v1\", \"name\": \"wlr_virtual_keyboard_v1\", \"type\": \"keyboard\", \"repeat_delay\": 600, \"repeat_rate\": 25, \"xkb_layout_names\": [ \""...}
Alexays/Waybar#11 0x000055bd41f150a7 in operator() (__closure=<optimized out>) at ../src/modules/s...

</details>



<!-- START COPILOT CODING AGENT SUFFIX -->

- Fixes Alexays/Waybar#4777

<!-- START COPILOT CODING AGENT TIPS -->
---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more [Copilot coding agent tips](https://gh.io/copilot-coding-agent-tips) in the docs.