[Fix] Return nothing if no key given

bower.json

@@ -1,7 +1,7 @@
 {
   "name": "strolch-wc-localize-behavior",
   "description": "Strolch Polymer Localization Behavior extension",
-  "version": "1.1.11",
+  "version": "1.1.18",
   "authors": [
     "Franz Nieschalk",
     "Robert von Burg"
@@ -20,7 +20,7 @@
   "homepage": "https://github.com/strolch-li/strolch-wc-localize-behavior",
   "ignore": [],
   "dependencies": {
-    "strolchjs": "strolch-li/strolchjs#^0.4.3",
+    "strolchjs": "strolch-li/strolchjs#^0.5.3",
 
     "app-localize-behavior": "PolymerElements/app-localize-behavior#^1.0.2"
   }

strolch-wc-localize-behavior.html

@@ -4,18 +4,46 @@
 
     // custom behaviour accessing the configuration above
     StrolchLocalizeBehaviorImpl = {
-        attached: function () {
-            var locale = Strolch.getUserLocale();
-            //console.log("Initializing for '" + this.localName + "' for locale " + locale + " and path " + this.localesPath);
+        properties: {
+            fallbackLanguage: {
+                type: String,
+                value: "en"
+            }
+        },
+        created: function () {
+            this.__computeLocalizeOld = this.__computeLocalize;
+            this.__computeLocalize = function (language, resources, formats) {
+                var localizeFunc;
+                if (!resources[language])
+                    localizeFunc = this.__computeLocalizeOld(this.fallbackLanguage, resources, formats).bind(this);
+                localizeFunc = this.__computeLocalizeOld(language, resources, formats).bind(this);
 
+                return function () {
+                    var key = arguments[0];
+                    if(!key)
+                        return;
+                    if (!resources || !language || !resources[language])
+                        return key;
+
+                    try {
+                        return localizeFunc.apply(this, arguments);
+                    } catch (e) {
+                        console.log("Failed to translate key " + key);
+                        console.log(e);
+                        return key;
+                    }
+                }.bind(this);
+            }.bind(this);
+        },
+        attached: function () {
             // load the language resource of the configured language
-            this.language = locale;
+            this.language = Strolch.getUserLocale();
             this.useKeyIfMissing = true;
 
             if (Strolch.isNotEmptyString(this.localesPath)) {
                 this.loadResources(this.resolveUrl(this.localesPath));
             }
-        }
+        },
     };
 
     // inherit the behavior of the standard polymer localization