fix err in abstract class

lib/abstract-class.js

@@ -1206,6 +1206,7 @@ AbstractClass.hasMany = function hasMany(anotherClass, params) {
  * This optional parameter default value is false, so the related object will be loaded from cache if available.
  */
 AbstractClass.belongsTo = function (anotherClass, params) {
+    var modelName = this.modelName;
     var methodName = params.as;
     var fk = params.foreignKey;
 
@@ -1217,7 +1218,7 @@ AbstractClass.belongsTo = function (anotherClass, params) {
         multiple: false
     };
 
-    this.schema.defineForeignKey(this.modelName, fk);
+    this.schema.defineForeignKey(modelName, fk);
     this.prototype['__finders__'] = this.prototype['__finders__'] || {};
 
     this.prototype['__finders__'][methodName] = function (id, cb) {
@@ -1226,10 +1227,14 @@ AbstractClass.belongsTo = function (anotherClass, params) {
             return;
         }
         anotherClass.findById(id, function (err, inst) {
+            if(!inst) {
+                return cb(new Error(modelName + ' belongsTo ' + anotherClass.modelName + ' via foreign key ' + fk + ' error'));
+            }
             var sid = typeof inst.id === 'object' ? inst.id.toString() : inst.id;
             var fid = typeof this[fk] === 'object' ? this[fk].toString() : this[fk];
-            if (err)
+            if (err) {
                 return cb(err);
+            }
             if (!inst)
                 return cb(null, null);
             if (sid === fid) {

package.json

@@ -1,7 +1,7 @@
 {
   "name": "caminte",
   "description": "ORM for every database: redis, mysql, neo4j, mongodb, rethinkdb, postgres, sqlite, tingodb",
-  "version": "0.2.4",
+  "version": "0.2.5",
   "author": {
     "name": "Aleksej Gordejev",
     "email": "[email protected]",