Deploy 9.0.4

bower.json

@@ -1,6 +1,6 @@
 {
   "name": "yjs",
-  "version": "9.0.3",
+  "version": "9.0.4",
   "homepage": "y-js.org",
   "authors": [
     "Kevin Jahns <kevin.jahns@rwth-aachen.de>"

y.es6

@@ -2708,13 +2708,21 @@ function Y (opts/* :YOptions */) /* :Promise<YConfig> */ {
   }
   Y.sourceDir = opts.sourceDir
   return Y.requestModules(modules).then(function () {
-    return new Promise(function (resolve) {
-      var yconfig = new YConfig(opts)
-      yconfig.db.whenUserIdSet(function () {
-        yconfig.init(function () {
-          resolve(yconfig)
+    return new Promise(function (resolve, reject) {
+      if (opts == null) reject('An options object is expected! ')
+      else if (opts.connector == null) reject('You must specify a connector! (missing connector property)')
+      else if (opts.connector.name == null) reject('You must specify connector name! (missing connector.name property)')
+      else if (opts.db == null) reject('You must specify a database! (missing db property)')
+      else if (opts.connector.name == null) reject('You must specify db name! (missing db.name property)')
+      else if (opts.share == null) reject('You must specify a set of shared types!')
+      else {
+        var yconfig = new YConfig(opts)
+        yconfig.db.whenUserIdSet(function () {
+          yconfig.init(function () {
+            resolve(yconfig)
+          })
         })
-      })
+      }
     })
   })
 }