Include connection info on errors

[gabegorelick]

I have an app that connects to multiple PG instances. When a pg client/pool encounters an error, the only way to know which database was the culprit is to have a handle to the Client/Pool object. But often times your error handling code does not have a handle to the Client/Pool objects (by its nature, error handling code is often disconnected from the code that threw the error). The only thing error handling has a handle to is the error itself.

An example:

try { 
  await doSomethingWithVariableDb();
} catch (err) {
 // This does not currently work.
  console.error("Error doing something with DB " + err.host);
}

It would be nice if pg included this target host info on errors. Alternatively, pg could include the associated Client and/or Pool object on the error. Although that seems more prone to leaking memory.