Collect errors correctly

[snewcomer]

close #396

[josemarluedke]

@snewcomer Any specific reason for this change? It was super helpful to have the actual shape of the error here. I would suggest making a type (or an interface) specifically for the error.

Here is an example of a function that is written in TS which was working fine before this change:

  get errors(): string[] {
    const fieldErrors = this.args.changeset.errors.filter(error => {
      return error.key === this.fullFieldName;
    });

    return fieldErrors.reduce(
      (errors: string[], error: ValidationError): string[] => {
        return [...errors, ...error.validation];
      },
      []
    );
  }

Now typescript is not happy, with the following error:

Property 'key' does not exist on type 'object'.

25       return error.key === this.fullFieldName;

Probably the same would apply for changes above.

[snewcomer]

This should be an easy fix...