Move initialization to constructor (#2503)

Fixes #2502

lib/winston/transports/console.js

@@ -18,13 +18,6 @@ const TransportStream = require('winston-transport');
  * @extends {TransportStream}
  */
 module.exports = class Console extends TransportStream {
-  // Keep a reference to the log, warn, and error console methods
-  // in case they get redirected to this transport after the logger is
-  // instantiated. This prevents a circular reference issue.
-  _consoleLog = console.log.bind(console);
-  _consoleWarn = console.warn.bind(console);
-  _consoleError = console.error.bind(console);
-
   /**
    * Constructor function for the Console transport object responsible for
    * persisting log messages and metadata to a terminal or TTY.
@@ -40,6 +33,13 @@ module.exports = class Console extends TransportStream {
     this.eol = typeof options.eol === 'string' ? options.eol : os.EOL;
     this.forceConsole = options.forceConsole || false;
 
+    // Keep a reference to the log, warn, and error console methods
+    // in case they get redirected to this transport after the logger is
+    // instantiated. This prevents a circular reference issue.
+    this._consoleLog = console.log.bind(console);
+    this._consoleWarn = console.warn.bind(console);
+    this._consoleError = console.error.bind(console);
+
     this.setMaxListeners(30);
   }