fix eslint warns

Author: Anemy

lib/data-service.js

@@ -178,6 +178,7 @@ class DataService extends EventEmitter {
    * and options.
    *
    * @param {string} ns - The namespace to search on.
+   * @param {object} filter - The filter for the count.
    * @param {object} options - The query options.
    * @param {function} callback - The callback function.
    */

lib/native-client.js

@@ -104,7 +104,8 @@ class NativeClient extends EventEmitter {
     this.isMongos = false;
 
     const [
-      _client, // The client is set in the `setupListeners` method.
+      // eslint-disable-next-line no-unused-vars
+      _, // The client is set in the `setupListeners` method.
       connectionOptions
     ] = await connect(
       this.model,
@@ -294,7 +295,8 @@ class NativeClient extends EventEmitter {
    */
   collections(databaseName, callback) {
     if (databaseName === SYSTEM) {
-      return callback(null, []);
+      callback(null, []);
+      return;
     }
     this.collectionNames(databaseName, (error, names) => {
       if (error) {
@@ -514,6 +516,7 @@ class NativeClient extends EventEmitter {
 
   /**
    * Disconnect the client.
+   * @param {Function} callback - Callback called after connection closed.
    */
   disconnect(callback) {
     this.client.close(true, callback);