Add an assert.

src/parser/text_element_parser.rs

@@ -57,6 +57,8 @@ where
 {
     move |mut i: I| {
         let mut current_context = context.clone();
+        // Despite the clone, the Rc should still point to the same value, otherwise we'll get stuck in an endless loop.
+        assert!(current_context.ptr_eq(context));
         loop {
             let len = i.input_len();
             match till_matcher(&current_context, i.clone()) {