bug: spec test throws error if mixin prop has a default value

[Altioc]

Prerequisites

• I have read the Contributing Guidelines.
• I agree to follow the Code of Conduct.
• I have searched for existing issues that already report this problem, without success.

Stencil Version

4.38.3

Current Behavior

If you run spec tests for a component that uses a Mixin that defines a prop with a default value then it will fail with an error stating ReferenceError: Must call super constructor in derived class before accessing 'this' or returning from derived constructor

Expected Behavior

Spec continues as if the prop had been defined on the base component

System Info

System: node 20.12.1
    Platform: linux (6.1.43)
   CPU Model: AMD EPYC (2 cpus)
    Compiler: /project/workspace/node_modules/@stencil/core/compiler/stencil.js
       Build: 1762374454
     Stencil: 4.38.3 😋
  TypeScript: 5.9.3
      Rollup: 4.34.9
      Parse5: 7.2.1
      jQuery: 4.0.0-pre
      Terser: 5.37.0

Steps to Reproduce

npm install
npm run test

Code Reproduction URL

https://codesandbox.io/p/sandbox/crimson-start-r787w7

Additional Information

No response

[Altioc]

It would also appear that there is an issue calling @Event decorated properties. In this code sandbox if you run the spec tests it says that this.test is undefined

https://codesandbox.io/p/sandbox/angry-wood-4g8v4r