Index: trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/Functions.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/Functions.java	(revision 18875)
+++ trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/Functions.java	(revision 18876)
@@ -629,5 +629,5 @@
      */
     public static boolean has_tag_key(final Environment env, String key) {
-        return env.osm != null ? env.osm.hasKey(key) : false;
+        return env.osm != null && env.osm.hasKey(key);
     }
 
@@ -852,4 +852,7 @@
      */
     public static Boolean JOSM_search(final Environment env, String searchStr) {
+        if (env.osm == null) {
+            return null;
+        }
         Match m;
         try {