fix: use Record for properties field in Schema Object

[vaibhavrajsingh2001]

Using mapped types like { [propertyName: string]: SchemaObject | ReferenceObject } doesn't ensure the key to be of type string. Instead, TypeScript interprets the key as string | number.

This behaviour can be verified in the following playground

Due to this issue, if you iterate over the properties of a schema, TypeScript can't be sure that the key is of type string. Instead the key will be interpreted as of type string | number.

Using a Record allows to strictly type the key to only be of type string, which can be verified here

It's a known TypeScript issue https://github.com/microsoft/TypeScript/issues/48269

[vaibhavrajsingh2001]

Hey @pjmolina, came across this issue while I was trying to iterate over the properties field of a SchemaObject. Would appreciate a review here 🙏.

[pjmolina]

I have contradicting feelings here:

• We cannot fix TS or JS here (clearly out of scope)
• Having a string key in dictionary does not prevent for accessing the keys by index (JS semantics) nor we should forbid it.
• If we fix this one, we should be coherent and fix all dictionary-like access we use.

To be honest, not sure if it is makes worthy. And if we are breaking uses cases for anyone else.