set Error.cause and other properties as "extras"

[mmkal]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows Conventional Commits
• Tests for the changes have been added (for bug fixes / features) - I made this change in the browser, but this PR is really just a starting point. Sadly I don't think I'll find the time to clone the repo locally, get the tests running etc.
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Refactoring (no functional changes, no api changes)
• Other... Please describe:

What is the current behavior?

See ticket below

Closes #17

What is the new behavior?

Set cause as part of extras

Does this PR introduce a breaking change?

• Yes
• No

Other information

[splincode]

@sevaru Could you review please?

[sevaru]

Thank you for your pull request and the effort you've put into it!

Upon review, we've noticed behavior differences with the native Sentry client, particularly regarding the cause field and extra error data handling.

To align with our goal of keeping micro-sentry code and request data minimal, your suggestion to extend a class and override the prepare method is the best approach for now.

Highlights:

• Cause Field: We follow the native Sentry client's approach to unwrap errors, using plugins like LinkedErrors.

{
  "exception": {
    "values": [
      {
        "type": "Error",
        "value": "cause exception text"
        // ...
      },
      {
        "type": "Error",
        "value": "parent error"
        // ...
      }
    ]
  }
  // ...
}

• Extra Error Data: Instead of attaching additional fields to extras, we use contexts, as per the ExtraErrorData plugin.

{
  "contexts": {
    // ...
    "Error": { "myField": "myField" }
  }
}

Moving Forward:

We're considering adding more flexible plugin capabilities in the future, similar to your contribution.

Let us know if you interested in trying out the new plugin system once it's available!