feat(xatu): reject files with parse errors

src/xatu/xatu.rs

@@ -13,6 +13,13 @@ pub fn run(files: Vec<SourceFile>) -> status::Result<()> {
         let file = store.get(file_id);
         let parsed = parser::parse_file(file_id, &file.source);
 
+        if !parsed.errors.is_empty() {
+            return Err(status::Status::failed_precondition(format!(
+                "failed to parse {}",
+                file.path.display()
+            )));
+        }
+
         for diagnostic in rules::run_rules(&parsed) {
             println!(
                 "{}:{}..{}: {}: {}",