refactor(pool): move connect error debug logging to call site

We previously emitted a debug message when a connection failed in the `Connection.connect` method. Now that we have moved all initialization to a single method, it's more appropriate to move the debug message to the `connect` call site's error case.

Author: mbroadst

lib/connection/pool.js

@@ -385,6 +385,10 @@ function attemptReconnect(self) {
  self.connectingConnections--;
 
  if (err) {
+ if (self.logger.isDebug()) {
+ self.logger.debug(`connection attempt failed with error [${JSON.stringify(err)}]`);
+ }
+
  self.retriesLeft = self.retriesLeft - 1;
  if (self.retriesLeft <= 0) {
  self.destroy();
@@ -705,6 +709,10 @@ Pool.prototype.connect = function(credentials) {
  self.connectingConnections--;
 
  if (err) {
+ if (self.logger.isDebug()) {
+ self.logger.debug(`connection attempt failed with error [${JSON.stringify(err)}]`);
+ }
+
  // NOTE: when `err` exists, `connection` is actually the originating event name
  connectionFailureHandler(self, connection, err);
  return;
@@ -1276,6 +1284,10 @@ function _createConnection(self) {
  self.connectingConnections--;
 
  if (err) {
+ if (self.logger.isDebug()) {
+ self.logger.debug(`connection attempt failed with error [${JSON.stringify(err)}]`);
+ }
+
  if (!self.reconnectId && self.options.reconnect) {
  self.reconnectId = setTimeout(attemptReconnect(self), self.options.reconnectInterval);
  }