Destroy socket when there was an error on it

When error happens on socket, potentially dead socket is kept open indefinitely by calling "connection.end()".
Similar issue is that it keeps socket open until long-running query is finished even though the connection was ended.

Author: Gobie

lib/client.js

@@ -538,7 +538,7 @@ Client.prototype.query = function (config, values, callback) {
 Client.prototype.end = function (cb) {
   this._ending = true
 
-  if (this.activeQuery) {
+  if (this.activeQuery || !this._queryable) {
     // if we have an active query we need to force a disconnect
     // on the socket - otherwise a hung query could block end forever
     this.connection.stream.destroy()

test/integration/connection-pool/error-tests.js

@@ -99,3 +99,17 @@ suite.test('connection-level errors cause future queries to fail', (cb) => {
     }))
   }))
 })
+
+suite.test('handles socket error during pool.query and destroys it immediately', (cb) => {
+  const pool = new pg.Pool({ max: 1 })
+  pool.query('SELECT pg_sleep(10)', [], (err) => {
+    assert.equal(err.message, 'network issue')
+    assert.equal(stream.destroyed, true)
+    cb()
+  })
+
+  const stream = pool._clients[0].connection.stream
+  setTimeout(() => {
+    stream.emit('error', new Error('network issue'))
+  }, 100)
+})