Incorrect type definitions causing confusion when trying to catch PostgresError

I noticed that when I want to catch an error and identify it using instanceof I got an error TypeError: Right-hand side of 'instanceof' is not an object. Which was caused by following code:

import { PostgresError } from 'postgres';

try {
  // await query
} catch (e) {
  if (e instanceof PostgresError) {
    // do something
  }
}

To fix that I had to use default import:

import Postgres from 'postgres';

try {
  // await query
} catch (e) {
  if (e instanceof Postgres.PostgresError) {
    // do something
  }
}

This is confusing because typescript was not able to catch the failing example as something wrong and I was able to find this error only in runtime.

Start by reproducing the two import forms shown in the issue and inspect how the package exposes PostgresError to TypeScript. The type definitions should accurately represent the runtime export so the named-import example cannot lead to the reported instanceof failure; verify the corrected behavior with the same catch block.