Merge pull request #430 from 5225225/json-path-fix

Fix out of bounds index when parsing JSON path

src/json/path.rs

@@ -74,7 +74,7 @@ fn get_local_path_and_level(paths: &[PathSeg]) -> Option<(usize, String)> {
     paths.get(0).and_then(|seg| {
         if seg == &PathSeg::Ruled(Rule::path_local) {
             let mut level = 0;
-            while paths[level + 1] == PathSeg::Ruled(Rule::path_up) {
+            while paths.get(level + 1)? == &PathSeg::Ruled(Rule::path_up) {
                 level += 1;
             }
             if let Some(PathSeg::Named(name)) = paths.get(level + 1) {

tests/subexpression.rs

@@ -53,3 +53,17 @@ fn test_subexpression() {
         "Success"
     );
 }
+
+#[test]
+fn invalid_json_path() {
+    // The data here is not important
+    let data = &Vec::<()>::new();
+
+    let hbs = Handlebars::new();
+
+    let error = hbs.render_template("{{x[]@this}}", &data).unwrap_err();
+
+    let expected = "Error rendering \"Unnamed template\" line 1, col 1: Helper not defined: \"x\"";
+
+    assert_eq!(format!("{}", error), expected);
+}