code: improve error handling consistency

 river/Control.zig           |  2 +-
 river/Cursor.zig            |  6 ++----
 river/DecorationManager.zig |  2 +-
 river/InputManager.zig      |  3 +--
 river/Keyboard.zig          |  6 ++----
 river/Output.zig            | 10 ++--------
 river/Root.zig              | 12 ++++--------
 river/Seat.zig              |  5 ++---
 river/Server.zig            |  8 ++++----
 river/StatusManager.zig     |  2 +-
 riverctl/main.zig           |  7 +++----
 11 files changed, 23 insertions(+), 40 deletions(-)

diff --git a/river/Control.zig b/river/Control.zig
index d84f519..2b8ee4d 100644
--- a/river/Control.zig
+++ b/river/Control.zig
@@ -47,7 +47,7 @@ pub fn init(self: *Self, server: *Server) !void {
         protocol_version,
         self,
         bind,
-    ) orelse return error.CantCreateWlGlobal;
+    ) orelse return error.OutOfMemory;
 
     self.args_map = std.AutoHashMap(u32, std.ArrayList([]const u8)).init(util.gpa);
 
diff --git a/river/Cursor.zig b/river/Cursor.zig
index 18bb9bf..e826952 100644
--- a/river/Cursor.zig
+++ b/river/Cursor.zig
@@ -59,15 +59,13 @@ pub fn init(self: *Self, seat: *Seat) !void {
     self.seat = seat;
 
     // Creates a wlroots utility for tracking the cursor image shown on screen.
-    self.wlr_cursor = c.wlr_cursor_create() orelse
-        return error.CantCreateWlrCursor;
+    self.wlr_cursor = c.wlr_cursor_create() orelse return error.OutOfMemory;
 
     // Creates an xcursor manager, another wlroots utility which loads up
     // Xcursor themes to source cursor images from and makes sure that cursor
     // images are available at all scale factors on the screen (necessary for
     // HiDPI support). We add a cursor theme at scale factor 1 to begin with.
-    self.wlr_xcursor_manager = c.wlr_xcursor_manager_create(null, 24) orelse
-        return error.CantCreateWlrXCursorManager;
+    self.wlr_xcursor_manager = c.wlr_xcursor_manager_create(null, 24) orelse return error.OutOfMemory;
     c.wlr_cursor_attach_output_layout(self.wlr_cursor, seat.input_manager.server.root.wlr_output_layout);
     if (c.wlr_xcursor_manager_load(self.wlr_xcursor_manager, 1) == 0) {
         if (build_options.xwayland) {
diff --git a/river/DecorationManager.zig b/river/DecorationManager.zig
index 1b844e9..2eb1509 100644
--- a/river/DecorationManager.zig
+++ b/river/DecorationManager.zig
@@ -33,7 +33,7 @@ listen_new_toplevel_decoration: c.wl_listener,
 
 pub fn init(self: *Self, server: *Server) !void {
     self.wlr_xdg_decoration_manager = c.wlr_xdg_decoration_manager_v1_create(server.wl_display) orelse
-        return error.CantCreateWlrXdgDecorationManager;
+        return error.OutOfMemory;
 
     self.listen_new_toplevel_decoration.notify = handleNewToplevelDecoration;
     c.wl_signal_add(
diff --git a/river/InputManager.zig b/river/InputManager.zig
index 9c0895c..10293ea 100644
--- a/river/InputManager.zig
+++ b/river/InputManager.zig
@@ -46,8 +46,7 @@ pub fn init(self: *Self, server: *Server) !void {
 
     // This is automatically freed when the display is destroyed
     self.wlr_input_inhibit_manager =
-        c.wlr_input_inhibit_manager_create(server.wl_display) orelse
-        return error.CantCreateInputInhibitManager;
+        c.wlr_input_inhibit_manager_create(server.wl_display) orelse return error.OutOfMemory;
 
     self.seats = std.TailQueue(Seat).init();
 
diff --git a/river/Keyboard.zig b/river/Keyboard.zig
index 12b043f..6fab20f 100644
--- a/river/Keyboard.zig
+++ b/river/Keyboard.zig
@@ -46,16 +46,14 @@ pub fn init(self: *Self, seat: *Seat, wlr_input_device: *c.wlr_input_device) !vo
         .variant = null,
         .options = null,
     };
-    const context = c.xkb_context_new(.XKB_CONTEXT_NO_FLAGS) orelse
-        return error.CantCreateXkbContext;
+    const context = c.xkb_context_new(.XKB_CONTEXT_NO_FLAGS) orelse return error.CreateXkbContextError;
     defer c.xkb_context_unref(context);
 
     const keymap = c.xkb_keymap_new_from_names(
         context,
         &rules,
         .XKB_KEYMAP_COMPILE_NO_FLAGS,
-    ) orelse
-        return error.CantCreateXkbKeymap;
+    ) orelse return error.CreateXkbKeymapError;
     defer c.xkb_keymap_unref(keymap);
 
     // TODO: handle failure after https://github.com/swaywm/wlroots/pull/2081
diff --git a/river/Output.zig b/river/Output.zig
index 5ac7306..2f0398e 100644
--- a/river/Output.zig
+++ b/river/Output.zig
@@ -82,16 +82,10 @@ pub fn init(self: *Self, root: *Root, wlr_output: *c.wlr_output) !void {
     // refresh rate), and each monitor supports only a specific set of modes. We
     // just pick the monitor's preferred mode, a more sophisticated compositor
     // would let the user configure it.
-
-    // if not empty
-    if (c.wl_list_empty(&wlr_output.modes) == 0) {
-        // TODO: handle failure
-        const mode = c.wlr_output_preferred_mode(wlr_output);
+    if (c.wlr_output_preferred_mode(wlr_output)) |mode| {
         c.wlr_output_set_mode(wlr_output, mode);
         c.wlr_output_enable(wlr_output, true);
-        if (!c.wlr_output_commit(wlr_output)) {
-            return error.CantCommitWlrOutputMode;
-        }
+        if (!c.wlr_output_commit(wlr_output)) return error.OutputCommitFailed;
     }
 
     self.root = root;
diff --git a/river/Root.zig b/river/Root.zig
index c5301a8..7bcb83e 100644
--- a/river/Root.zig
+++ b/river/Root.zig
@@ -56,19 +56,15 @@ pub fn init(self: *Self, server: *Server) !void {
 
     // Create an output layout, which a wlroots utility for working with an
     // arrangement of screens in a physical layout.
-    self.wlr_output_layout = c.wlr_output_layout_create() orelse
-        return error.CantCreateWlrOutputLayout;
+    self.wlr_output_layout = c.wlr_output_layout_create() orelse return error.OutOfMemory;
     errdefer c.wlr_output_layout_destroy(self.wlr_output_layout);
 
     self.outputs = std.TailQueue(Output).init();
 
-    const noop_wlr_output = c.river_wlr_noop_add_output(server.noop_backend) orelse
-        return error.CantAddNoopOutput;
+    const noop_wlr_output = c.river_wlr_noop_add_output(server.noop_backend) orelse return error.OutOfMemory;
     try self.noop_output.init(self, noop_wlr_output);
 
-    if (build_options.xwayland) {
-        self.xwayland_unmanaged_views = std.TailQueue(XwaylandUnmanaged).init();
-    }
+    if (build_options.xwayland) self.xwayland_unmanaged_views = std.TailQueue(XwaylandUnmanaged).init();
 
     self.pending_configures = 0;
 
@@ -76,7 +72,7 @@ pub fn init(self: *Self, server: *Server) !void {
         self.server.wl_event_loop,
         handleTimeout,
         self,
-    ) orelse return error.CantCreateTimer;
+    ) orelse return error.AddTimerError;
 }
 
 pub fn deinit(self: *Self) void {
diff --git a/river/Seat.zig b/river/Seat.zig
index d025921..9991963 100644
--- a/river/Seat.zig
+++ b/river/Seat.zig
@@ -75,12 +75,11 @@ pub fn init(self: *Self, input_manager: *InputManager, name: []const u8) !void {
     self.input_manager = input_manager;
 
     // This will be automatically destroyed when the display is destroyed
-    self.wlr_seat = c.wlr_seat_create(input_manager.server.wl_display, name.ptr) orelse
-        return error.CantCreateWlrSeat;
+    self.wlr_seat = c.wlr_seat_create(input_manager.server.wl_display, name.ptr) orelse return error.OutOfMemory;
     self.wlr_seat.data = self;
 
     try self.cursor.init(self);
-    errdefer self.cursor.destroy();
+    errdefer self.cursor.deinit();
 
     self.keyboards = std.TailQueue(Keyboard).init();
 
diff --git a/river/Server.zig b/river/Server.zig
index 7269b96..b31858a 100644
--- a/river/Server.zig
+++ b/river/Server.zig
@@ -145,11 +145,11 @@ pub fn deinit(self: *Self) void {
 
 /// Create the socket, start the backend, and setup the environment
 pub fn start(self: Self) !void {
-    const socket = c.wl_display_add_socket_auto(self.wl_display) orelse return error.CantAddSocket;
-    if (!c.river_wlr_backend_start(self.wlr_backend)) return error.CantStartBackend;
-    if (c.setenv("WAYLAND_DISPLAY", socket, 1) < 0) return error.CantSetEnv;
+    const socket = c.wl_display_add_socket_auto(self.wl_display) orelse return error.AddSocketError;
+    if (!c.river_wlr_backend_start(self.wlr_backend)) return error.StartBackendError;
+    if (c.setenv("WAYLAND_DISPLAY", socket, 1) < 0) return error.SetenvError;
     if (build_options.xwayland) {
-        if (c.setenv("DISPLAY", &self.wlr_xwayland.display_name, 1) < 0) return error.CantSetEnv;
+        if (c.setenv("DISPLAY", &self.wlr_xwayland.display_name, 1) < 0) return error.SetenvError;
     }
 }
 
diff --git a/river/StatusManager.zig b/river/StatusManager.zig
index 4c789e1..7481f3c 100644
--- a/river/StatusManager.zig
+++ b/river/StatusManager.zig
@@ -51,7 +51,7 @@ pub fn init(self: *Self, server: *Server) !void {
         protocol_version,
         self,
         bind,
-    ) orelse return error.CantCreateWlGlobal;
+    ) orelse return error.OutOfMemory;
 
     self.listen_display_destroy.notify = handleDisplayDestroy;
     c.wl_display_add_destroy_listener(server.wl_display, &self.listen_display_destroy);
diff --git a/riverctl/main.zig b/riverctl/main.zig
index 8e02a06..ec804d7 100644
--- a/riverctl/main.zig
+++ b/riverctl/main.zig
@@ -36,11 +36,10 @@ var river_control_optional: ?*c.zriver_control_v1 = null;
 var wl_seat_optional: ?*c.wl_seat = null;
 
 pub fn main() !void {
-    const wl_display = c.wl_display_connect(null) orelse return error.CantConnectToDisplay;
+    const wl_display = c.wl_display_connect(null) orelse return error.ConnectError;
     const wl_registry = c.wl_display_get_registry(wl_display);
 
-    if (c.wl_registry_add_listener(wl_registry, &wl_registry_listener, null) < 0)
-        return error.FailedToAddListener;
+    if (c.wl_registry_add_listener(wl_registry, &wl_registry_listener, null) < 0) unreachable;
     if (c.wl_display_roundtrip(wl_display) < 0) return error.RoundtripFailed;
 
     const river_control = river_control_optional orelse return error.RiverControlNotAdvertised;
@@ -56,7 +55,7 @@ pub fn main() !void {
         command_callback,
         &command_callback_listener,
         null,
-    ) < 0) return error.FailedToAddListener;
+    ) < 0) unreachable;
 
     // Loop until our callback is called and we exit.
     while (true) if (c.wl_display_dispatch(wl_display) < 0) return error.DispatchFailed;