fix invalid free

src/core/observable.zig

@@ -12,7 +12,7 @@ pub fn Observable(T: type) type {
         }
 
         pub fn deinit(self: *Self) void {
-            for(self.observers)|o| {
+            for(self.observers.items)|o| {
                 self.allocator.destroy(o);
             }
             self.observers.deinit();