chore(frontends/lean/definition_cmds): update comment

src/frontends/lean/definition_cmds.cpp

@@ -629,7 +629,7 @@ public:
                 throw exception("not a rfl-lemma, even though marked as rfl");
             return inline_new_defs(m_decl_env, elab.env(), val);
         } catch (exception & ex) {
-            // TODO(gabriel,leo): remove this catch block after single threaded queue discard bad tasks
+            /* Remark: we need the catch to be able to produce correct line information */
             message_builder error_msg(&m_pos_provider, tc, m_decl_env, get_global_ios(),
                                       m_pos_provider.get_file_name(), m_pos_provider.get_some_pos(),
                                       ERROR);