Error contains un-typed properties

[HopefulLlama]

Issue Description

What are you doing?

Attempting to access .parent.detail property of an error.

const errorMessage = error.parent.detail;

What do you expect to happen?

I wanted to get this property without any Type errors from TypeScript!

What is actually happening?

The output was that TypeScript complains about missing properties, and that I needed to amend the code (losing type safety) as such!

const errorMessage = (error as any).parent.detail;

Additional context

Add any other context or screenshots about the feature request here.

Environment

• Sequelize version: 5.18.4
• Node.js version: 12.9.1
• Operating System: MacOS Sierra
• If TypeScript related: TypeScript version: 3.6.3

Issue Template Checklist

How does this problem relate to dialects?

• I think this problem happens regardless of the dialect.
• I think this problem happens only for the following dialect(s):
• I don't know, I was using PUT-YOUR-DIALECT-HERE, with connector library version XXX and database version XXX

Would you be willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time and I know how to start.
• Yes, I have the time but I don't know how to start, I would need guidance.
• No, I don't have the time, although I believe I could do it if I had the time...
• No, I don't have the time and I wouldn't even know how to start.

[github-actions]

This issue has been automatically marked as stale because it has been open for 7 days without activity. It will be closed if no further activity occurs. If this is still an issue, just leave a comment or remove the "stale" label. 🙂