screen: add error union to return type

src/Screen.zig

···
 mouse_shape: Shape = .default,
 cursor_shape: Cell.CursorShape = .default,
 
-pub fn init(alloc: std.mem.Allocator, winsize: Winsize, unicode: *const Unicode) !Screen {
+pub fn init(alloc: std.mem.Allocator, winsize: Winsize, unicode: *const Unicode) std.mem.Allocator.Error!Screen {
     const w = winsize.cols;
     const h = winsize.rows;
     const self = Screen{

src/View.zig

···
 };
 
 /// Initialize a new View
-pub fn init(alloc: mem.Allocator, unicode: *const Unicode, config: Config) !View {
+pub fn init(alloc: mem.Allocator, unicode: *const Unicode, config: Config) mem.Allocator.Error!View {
     const screen = try Screen.init(
         alloc,
         .{
···
     x = @min(x, self.screen.width -| width);
     y = @min(y, self.screen.height -| height);
     const child = win.child(.{
-        .x_off = x,
-        .y_off = y,
         .width = .{ .limit = width },
         .height = .{ .limit = height },
     });
-    self.draw(child, .{});
+    self.draw(child, .{ .x_off = x, .y_off = y });
     return .{ x, y };
 }