[fix] emit an error if proper URL is not passed in as a target

Author: jcrugzz

Diff for: lib/http-proxy/index.js

@@ -64,7 +64,9 @@ function createRightProxy(type) {
           options[e] = parse_url(options[e]);
       });
 
-      if(typeof this.emit === 'undefined' && !cbl) { throw new Error("You need to pass a callback to handle errors") }
+      if (!options.target && !options.forward) {
+        return this.emit('error', new Error('Must provide a proper URL as target'));
+      }
 
       for(var i=0; i < passes.length; i++) {
         /**