Add vm.new_name_error helper

vm/src/frame.rs

@@ -1090,10 +1090,7 @@ impl Frame {
         let value = match optional_value {
             Some(value) => value,
             None => {
-                let name_error_type = vm.ctx.exceptions.name_error.clone();
-                let msg = format!("name '{}' is not defined", name);
-                let name_error = vm.new_exception(name_error_type, msg);
-                return Err(name_error);
+                return Err(vm.new_name_error(format!("name '{}' is not defined", name)));
             }
         };
 

vm/src/vm.rs

@@ -186,6 +186,11 @@ impl VirtualMachine {
         self.new_exception(type_error, msg)
     }
 
+    pub fn new_name_error(&self, msg: String) -> PyObjectRef {
+        let name_error = self.ctx.exceptions.name_error.clone();
+        self.new_exception(name_error, msg)
+    }
+
     pub fn new_unsupported_operand_error(
         &self,
         a: PyObjectRef,