notification: fixed error when there was no linkinformation available

(cherry picked from commit c0af5de7)

entity/Notification_entity/entityfields/linkcontext/valueProcess.js

@@ -3,4 +3,5 @@ import("system.result");
 import("system.text");
 
 var context = text.decodeMS(vars.get("$field.LINKINFO"))[0];
-result.string(context);
\ No newline at end of file
+if (context)
+    result.string(context);
\ No newline at end of file

entity/Notification_entity/entityfields/linkid/valueProcess.js

@@ -3,4 +3,5 @@ import("system.result");
 import("system.text");
 
 var id = text.decodeMS(vars.get("$field.LINKINFO"))[1];
-result.string(id);
\ No newline at end of file
+if (id)
+    result.string(id);
\ No newline at end of file