Improve error message when the requested V-Sync mode cannot be used

doc/classes/DisplayServer.xml

@@ -1049,7 +1049,7 @@
 			<return type="int" enum="DisplayServer.VSyncMode" />
 			<argument index="0" name="window_id" type="int" default="0" />
 			<description>
-				Returns the VSync mode of the given window.
+				Returns the V-Sync mode of the given window.
 			</description>
 		</method>
 		<method name="window_move_to_foreground">
@@ -1234,7 +1234,7 @@
 			<argument index="0" name="vsync_mode" type="int" enum="DisplayServer.VSyncMode" />
 			<argument index="1" name="window_id" type="int" default="0" />
 			<description>
-				Sets the VSync mode of the given window.
+				Sets the V-Sync mode of the given window.
 				See [enum DisplayServer.VSyncMode] for possible values and how they affect the behavior of your application.
 				Depending on the platform and used renderer, the engine will fall back to [constant VSYNC_ENABLED], if the desired mode is not supported.
 			</description>

doc/classes/ProjectSettings.xml

@@ -588,7 +588,7 @@
 			[b]Note:[/b] By default, or when set to 0, the initial window width is the viewport [member display/window/size/viewport_width]. This setting is ignored on iOS, Android, and HTML5.
 		</member>
 		<member name="display/window/vsync/vsync_mode" type="int" setter="" getter="" default="1">
-			Sets the VSync mode for the main game window.
+			Sets the V-Sync mode for the main game window.
 			See [enum DisplayServer.VSyncMode] for possible values and how they affect the behavior of your application.
 			Depending on the platform and used renderer, the engine will fall back to [code]Enabled[/code], if the desired mode is not supported.
 		</member>

drivers/vulkan/vulkan_context.cpp

@@ -1666,7 +1666,22 @@ Error VulkanContext::_update_swap_chain(Window *window) {
 	if (present_mode_available) {
 		window->presentMode = requested_present_mode;
 	} else {
-		WARN_PRINT("Requested VSync mode is not available!");
+		String present_mode_string;
+		switch (window->vsync_mode) {
+			case DisplayServer::VSYNC_MAILBOX:
+				present_mode_string = "Mailbox";
+				break;
+			case DisplayServer::VSYNC_ADAPTIVE:
+				present_mode_string = "Adaptive";
+				break;
+			case DisplayServer::VSYNC_ENABLED:
+				present_mode_string = "Enabled";
+				break;
+			case DisplayServer::VSYNC_DISABLED:
+				present_mode_string = "Disabled";
+				break;
+		}
+		WARN_PRINT(vformat("The requested V-Sync mode %s is not available. Falling back to V-Sync mode Enabled.", present_mode_string));
 		window->vsync_mode = DisplayServer::VSYNC_ENABLED; // Set to default.
 	}
 
@@ -2471,12 +2486,12 @@ String VulkanContext::get_device_pipeline_cache_uuid() const {
 }
 
 DisplayServer::VSyncMode VulkanContext::get_vsync_mode(DisplayServer::WindowID p_window) const {
-	ERR_FAIL_COND_V_MSG(!windows.has(p_window), DisplayServer::VSYNC_ENABLED, "Could not get VSync mode for window with WindowID " + itos(p_window) + " because it does not exist.");
+	ERR_FAIL_COND_V_MSG(!windows.has(p_window), DisplayServer::VSYNC_ENABLED, "Could not get V-Sync mode for window with WindowID " + itos(p_window) + " because it does not exist.");
 	return windows[p_window].vsync_mode;
 }
 
 void VulkanContext::set_vsync_mode(DisplayServer::WindowID p_window, DisplayServer::VSyncMode p_mode) {
-	ERR_FAIL_COND_MSG(!windows.has(p_window), "Could not set VSync mode for window with WindowID " + itos(p_window) + " because it does not exist.");
+	ERR_FAIL_COND_MSG(!windows.has(p_window), "Could not set V-Sync mode for window with WindowID " + itos(p_window) + " because it does not exist.");
 	windows[p_window].vsync_mode = p_mode;
 	_update_swap_chain(&windows[p_window]);
 }

servers/display_server.cpp

@@ -494,11 +494,11 @@ int64_t DisplayServer::window_get_native_handle(HandleType p_handle_type, Window
 }
 
 void DisplayServer::window_set_vsync_mode(DisplayServer::VSyncMode p_vsync_mode, WindowID p_window) {
-	WARN_PRINT("Changing the VSync mode is not supported by this display server.");
+	WARN_PRINT("Changing the V-Sync mode is not supported by this display server.");
 }
 
 DisplayServer::VSyncMode DisplayServer::window_get_vsync_mode(WindowID p_window) const {
-	WARN_PRINT("Changing the VSync mode is not supported by this display server.");
+	WARN_PRINT("Changing the V-Sync mode is not supported by this display server.");
 	return VSyncMode::VSYNC_ENABLED;
 }