fix(log): error ended up in unreadable errors

Fixes #524
Fixes #521

Author: wzrdtales

lib/commands/on-complete.js

@@ -8,12 +8,7 @@ module.exports = function (migrator, internals, callback, originalErr) {
 
   migrator.driver.close(function (err) {
     if ((err || originalErr) && typeof callback === 'function') {
-      callback(
-        new Error({
-          err: err,
-          originalErr: originalErr
-        })
-      );
+      callback(originalErr || err);
       return;
     } else {
       assert.ifError(originalErr);

lib/driver/index.js

@@ -74,15 +74,14 @@ exports.connect = function (config, intern, callback) {
         driver = require(req);
       } catch (e4) {
         return callback(
-          new Error({
-            stack:
-              'No such driver found, please try to install it via ' +
+          new Error(
+            'No such driver found, please try to install it via ' +
               'npm install db-migrate-' +
               config.driver +
               ' or ' +
               'npm install -g db-migrate-' +
               config.driver
-          })
+          )
         );
       }
     }