upd: remove nullptr from return value

src/Evalvisitor.cpp

@@ -131,7 +131,7 @@ std::any EvalVisitor::visitExpr_stmt(Python3Parser::Expr_stmtContext *ctx) {
         Variables.WriteVariable(ptr_var->name, old_val);
       }
     }
-    return nullptr;
+    return NoneType();
   }
   auto testlist_list = ctx->testlist();
   auto val = visitTestlist(testlist_list[testlist_list.size() - 1]);
@@ -159,7 +159,7 @@ std::any EvalVisitor::visitExpr_stmt(Python3Parser::Expr_stmtContext *ctx) {
       throw InterpretException(
           "visitExpr_stmt: Expect left value or tuple at the left of assign");
   }
-  return nullptr;
+  return NoneType();
 }
 
 std::any EvalVisitor::visitAugassign(Python3Parser::AugassignContext *ctx) {
@@ -171,7 +171,7 @@ std::any EvalVisitor::visitFlow_stmt(Python3Parser::Flow_stmtContext *ctx) {
   if (ctx->continue_stmt()) return visitContinue_stmt(ctx->continue_stmt());
   if (ctx->return_stmt()) return visitReturn_stmt(ctx->return_stmt());
   throw FatalError("Unknown flow statement");
-  return nullptr;
+  return NoneType();
 }
 
 std::any EvalVisitor::visitBreak_stmt(Python3Parser::Break_stmtContext *ctx) {
@@ -201,7 +201,7 @@ std::any EvalVisitor::visitCompound_stmt(
   if (ctx->while_stmt()) return visitWhile_stmt(ctx->while_stmt());
   if (ctx->funcdef()) return visitFuncdef(ctx->funcdef());
   throw FatalError("Unknown compound statement");
-  return nullptr;
+  return NoneType();
 }
 
 std::any EvalVisitor::visitIf_stmt(Python3Parser::If_stmtContext *ctx) {
@@ -215,7 +215,7 @@ std::any EvalVisitor::visitIf_stmt(Python3Parser::If_stmtContext *ctx) {
       return visitSuite(suite_list[i]);
   if (test_list.size() - suite_list.size() == -1)
     return visitSuite(suite_list[suite_list.size() - 1]);
-  return nullptr;
+  return NoneType();
 }
 
 std::any EvalVisitor::visitWhile_stmt(Python3Parser::While_stmtContext *ctx) {
@@ -230,7 +230,7 @@ std::any EvalVisitor::visitWhile_stmt(Python3Parser::While_stmtContext *ctx) {
       if (res_ptr->Status == RETURN) return *res_ptr;
     }
   }
-  return nullptr;
+  return NoneType();
 }
 
 std::any EvalVisitor::visitSuite(Python3Parser::SuiteContext *ctx) {