fix: check if property exists on object without executing

[hendrik-depauw-lemon]

Description

When populating the getters on a ReadModel, the getters are executed twice. Once where you would expect it, and once in an if statement to check if the property exists on the ReadModel. In this if statement, there is no check to see if the getter is a promise or not, so it is never awaited. When the getter-promise would eventually return an error, the whole Booster application crashes.

This PR thus fixes two things:

• Stops unnecessarily executing all getters on ReadModels twice
• Prevents the app from crashing when an async getter throws an error

Changes

Replaced source[key] !== undefined with key in source.

Checks

• Project Builds
• Project passes tests and checks
• Updated documentation accordingly

[what-the-diff]

PR Summary

• Bug Fix Documentation
  A new JSON file was added to accurately document a bug fix in one of our key software packages, @boostercloud/framework-core. The bug previously caused our application to abruptly stop working if there was an error in an asynchronous data-fetching operation on a ReadModel, a component that provides read access to the application's stored data.

• Code Improvement
  The instances.ts file was updated to enhance the way we check for the existence of properties in the source object in the processProperties function. This contributes to better data handling within our application.