Index: /trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletionCache.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletionCache.java	(revision 2959)
+++ /trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletionCache.java	(revision 2960)
@@ -147,8 +147,10 @@
                 if (item instanceof TaggingPreset.Check) {
                     TaggingPreset.Check ch = (TaggingPreset.Check) item;
+                    if (ch.key == null) continue;
                     presetTagCache.put(ch.key, OsmUtils.falseval);
                     presetTagCache.put(ch.key, OsmUtils.trueval);
                 } else if (item instanceof TaggingPreset.Combo) {
                     TaggingPreset.Combo co = (TaggingPreset.Combo) item;
+                    if (co.key == null || co.values == null) continue;
                     for (String value : co.values.split(",")) {
                         presetTagCache.put(co.key, value);
@@ -156,7 +158,9 @@
                 } else if (item instanceof TaggingPreset.Key) {
                     TaggingPreset.Key ky = (TaggingPreset.Key) item;
+                    if (ky.key == null || ky.value == null) continue;
                     presetTagCache.put(ky.key, ky.value);
                 } else if (item instanceof TaggingPreset.Text) {
                     TaggingPreset.Text tt = (TaggingPreset.Text) item;
+                    if (tt.key == null) continue;
                     presetTagCache.putVoid(tt.key);
                     if (tt.default_ != null && !tt.default_.equals("")) {