Index: trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java	(revision 14358)
+++ trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java	(revision 14360)
@@ -1168,8 +1168,10 @@
         if (tile.hasError() && getDisplaySettings().isShowErrors()) {
             String errorMessage = tr(tile.getErrorMessage());
-            if (!errorMessage.startsWith("Error") && !errorMessage.startsWith(tr("Error"))) {
-                errorMessage = tr("Error") + ": " + errorMessage;
-            }
-            myDrawString(g, errorMessage, x + 2, texty);
+            if (errorMessage != null) {
+                if (!errorMessage.startsWith("Error") && !errorMessage.startsWith(tr("Error"))) {
+                    errorMessage = tr("Error") + ": " + errorMessage;
+                }
+                myDrawString(g, errorMessage, x + 2, texty);
+            }
             //texty += 1 + fontHeight;
         }