mod: add missing inline function attribute

Correct example to use the actual `zterm.Error` type accordingly.

src/element.zig

@@ -20,13 +20,13 @@ pub fn Element(Event: type) type {
         };
 
         /// Resize the corresponding `Element` with the given *size*.
-        pub fn resize(this: @This(), size: Point) void {
+        pub inline fn resize(this: @This(), size: Point) void {
             if (this.vtable.resize) |resize_fn|
                 resize_fn(this.ptr, size);
         }
 
         /// Reposition the corresponding `Element` with the given *origin*.
-        pub fn reposition(this: @This(), origin: Point) void {
+        pub inline fn reposition(this: @This(), origin: Point) void {
             if (this.vtable.reposition) |reposition_fn|
                 reposition_fn(this.ptr, origin);
         }