Index: trunk/src/org/openstreetmap/josm/data/validation/ValidationTask.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/validation/ValidationTask.java	(revision 18824)
+++ trunk/src/org/openstreetmap/josm/data/validation/ValidationTask.java	(revision 18825)
@@ -35,5 +35,5 @@
     private final boolean beforeUpload;
     private boolean canceled;
-    private List<TestError> errors;
+    private final List<TestError> errors = new ArrayList<>();
     private BiConsumer<ValidationTask, Test> testConsumer;
 
@@ -122,5 +122,4 @@
         if (Utils.isEmpty(tests))
             return;
-        errors = new ArrayList<>();
         getProgressMonitor().setTicksCount(tests.size() * validatedPrimitives.size());
         int testCounter = 0;