Fix NautilusContext::from_file for python files (#2690)

Author: jejuisland87654

libafl/src/generators/nautilus.rs

@@ -89,9 +89,10 @@ impl NautilusContext {
         let grammar_file = grammar_file.as_ref();
         if grammar_file.extension().unwrap_or_default() == "py" {
             log::debug!("Creating NautilusContext from python grammar");
-            let ctx = python_grammar_loader::load_python_grammar(
+            let mut ctx = python_grammar_loader::load_python_grammar(
                 fs::read_to_string(grammar_file)?.as_str(),
             );
+            ctx.initialize(tree_depth);
             return Ok(Self { ctx });
         }
         log::debug!("Creating NautilusContext from json grammar");