Support plan

• which support plan is this issue covered by? (e.g. Community, Core, Plus, or Enterprise): Community
• is this issue currently blocking your project? (yes/no): no
• is this issue affecting a production system? (yes/no): no

Context

• node version: v12.16.1
• module version with issue: 16.1.8
• last module version without issue : Not sure
• environment (e.g. node, browser, native): Node
• used with (e.g. hapi application, another framework, standalone, ...): standalone
• any other relevant information:

What are you trying to achieve or the steps to reproduce?

The following snippet throws this.$_super.default is not a function

const J = require("./lib");

const J2 = J.extend({
  type: "object",
  base: J.object(),
  overrides: {
    label(...args) {
      this.$_super.label(...args);
    },
  },
});

console.log(
  J2.object({
    a: J2.number().default(1),
  })
    .default()
    .validate(undefined)
);

What was the result you got?

An error was thrown

What result did you expect?

Shouldn't throw any error. Looks like $_super is reset on every extend() call.