fix: add default error listeners

docs/pages/apis/pool.mdx

@@ -240,7 +240,8 @@ The number of queued requests waiting on a client when all clients are checked o
 Whenever the pool establishes a new client connection to the PostgreSQL backend it will emit the `connect` event with the newly connected client.
 
 <Alert>
-  The event listener does not wait for promises or async functions. If you want to run setup commands on each new client, use the `onConnect` option. (See documentation above.)
+  The event listener does not wait for promises or async functions. If you want to run setup commands on each new
+  client, use the `onConnect` option. (See documentation above.)
 </Alert>
 
 ### acquire
@@ -260,9 +261,8 @@ If the backend goes down or a network partition is encountered all the idle, con
 The error listener is passed the error as the first argument and the client upon which the error occurred as the 2nd argument. The client will be automatically terminated and removed from the pool, it is only passed to the error handler in case you want to inspect it.
 
 <Alert>
-  <div>You probably want to add an event listener to the pool to catch background errors!</div>
-  Just like other event emitters, if a pool emits an <code>error</code> event and no listeners are added node will emit an
-  uncaught error and potentially crash your node process.
+  The pool has a default no-op error listener so an idle client error does not become an uncaught exception. Add your
+  own listener to observe, log, or otherwise handle these background errors.
 </Alert>
 
 ### release

packages/pg-pool/README.md

@@ -234,11 +234,14 @@ const pool = new Pool()
 // attach an error handler to the pool for when a connected, idle client
 // receives an error by being disconnected, etc
 pool.on('error', function (error, client) {
-  // handle this in the same way you would treat process.on('uncaughtException')
+  // observe or otherwise handle the background error
   // it is supplied the error as well as the idle client which received the error
 })
 ```
 
+Pools include a default no-op error listener so an idle client error does not become an uncaught exception. Add your own
+listener to observe, log, or otherwise handle these background errors.
+
 #### connect
 
 Fired whenever the pool creates a **new** `pg.Client` instance and successfully connects it to the backend.

packages/pg-pool/index.js

@@ -66,6 +66,7 @@ function makeIdleListener(pool, client) {
 class Pool extends EventEmitter {
   constructor(options, Client) {
     super()
+    this.on('error', () => {})
     this.options = Object.assign({}, options)
 
     if (options != null && 'password' in options) {

packages/pg-pool/test/events.js

@@ -7,6 +7,26 @@ const it = require('mocha').it
 const Pool = require('../')
 
 describe('events', function () {
+  it('does not throw an unhandled error event', function () {
+    const pool = new Pool({ Client: mockClient() })
+    const expectedError = new Error('unexpected idle client error')
+
+    expect(() => pool.emit('error', expectedError)).to.not.throwException()
+  })
+
+  it('emits errors to user listeners', function () {
+    const pool = new Pool({ Client: mockClient() })
+    const expectedError = new Error('unexpected idle client error')
+    let emittedError
+
+    pool.on('error', function (error) {
+      emittedError = error
+    })
+    pool.emit('error', expectedError)
+
+    expect(emittedError).to.be(expectedError)
+  })
+
   it('emits connect before callback', function (done) {
     const pool = new Pool()
     let emittedClient = false

packages/pg/lib/client.js

@@ -50,6 +50,7 @@ function coerceNumberOrDefault(value, defaultValue) {
 class Client extends EventEmitter {
   constructor(config) {
     super()
+    this.on('error', () => {})
 
     this.connectionParameters = new ConnectionParameters(config)
     this.user = this.connectionParameters.user

packages/pg/lib/native/client.js

@@ -22,6 +22,7 @@ const queryQueueLengthDeprecationNotice = nodeUtils.deprecate(
 
 const Client = (module.exports = function (config) {
   EventEmitter.call(this)
+  this.on('error', () => {})
   config = config || {}
 
   this._Promise = config.Promise || global.Promise

packages/pg/test/native/evented-api-tests.js

@@ -6,6 +6,26 @@ const assert = require('assert')
 const suite = new helper.Suite()
 const test = suite.test.bind(suite)
 
+test('does not throw an unhandled error event', function () {
+  const client = new Client(helper.config)
+  const expectedError = new Error('unexpected idle client error')
+
+  assert.doesNotThrow(() => client.emit('error', expectedError))
+})
+
+test('emits errors to user listeners', function () {
+  const client = new Client(helper.config)
+  const expectedError = new Error('unexpected idle client error')
+  let emittedError
+
+  client.on('error', (error) => {
+    emittedError = error
+  })
+  client.emit('error', expectedError)
+
+  assert.strictEqual(emittedError, expectedError)
+})
+
 const setupClient = function () {
   const client = new Client(helper.config)
   client.connect()

packages/pg/test/unit/client/configuration-tests.js

@@ -10,6 +10,26 @@ const pgdatabase = process.env['PGDATABASE'] || process.env.USER
 const pgport = process.env['PGPORT'] || 5432
 
 test('client settings', function () {
+  test('does not throw an unhandled error event', function () {
+    const client = new Client()
+    const expectedError = new Error('unexpected idle client error')
+
+    assert.doesNotThrow(() => client.emit('error', expectedError))
+  })
+
+  test('emits errors to user listeners', function () {
+    const client = new Client()
+    const expectedError = new Error('unexpected idle client error')
+    let emittedError
+
+    client.on('error', (error) => {
+      emittedError = error
+    })
+    client.emit('error', expectedError)
+
+    assert.strictEqual(emittedError, expectedError)
+  })
+
   test('defaults', function () {
     const client = new Client()
     assert.equal(client.user, pguser)