Remove some duplicate code

src/entity.zig

@@ -68,19 +68,6 @@ pub fn Entity(comptime ctx: anytype) type {
             inline for (add, 0..) |a, i|
                 desc.add[i] = util.anyToId(ctx, a);
 
-            switch (@typeInfo(@TypeOf(add))) {
-                .Struct => |s| {
-                    if (s.is_tuple) {
-                        if (s.fields.len > c.FLECS_ID_DESC_MAX)
-                            @compileError("Adding more than FLECS_ID_DESC_MAX ids");
-                        inline for (add, 0..) |a, i|
-                            desc.add[i] = util.anyToId(ctx, a);
-                    } else if (s.fields.len > 0)
-                        @compileError("Expected tuple or empty struct, got '" ++ @typeName(@TypeOf(add)) ++ "'");
-                },
-                else => @compileError("Expected tuple or empty struct, got '" ++ @typeName(@TypeOf(add)) ++ "'"),
-            }
-
             const result = c.ecs_entity_init(world.raw, &desc);
             return Self.fromRaw(world, result);
         }