Do not parse closures when allow_anonymous_fn is false.

src/parser.rs

@@ -1862,7 +1862,7 @@ fn parse_unary(
         }
         // | ...
         #[cfg(not(feature = "no_function"))]
-        Token::Pipe | Token::Or => {
+        Token::Pipe | Token::Or if settings.allow_anonymous_fn => {
             let mut new_state = ParseState::new(
                 state.engine,
                 #[cfg(not(feature = "unchecked"))]
@@ -3353,6 +3353,8 @@ impl Engine {
         };
         let expr = parse_expr(input, &mut state, &mut functions, settings)?;
 
+        assert!(functions.is_empty());
+
         match input.peek().unwrap() {
             (Token::EOF, _) => (),
             // Return error if the expression doesn't end