Fixes a cache range error (#12645)

Change-Id: I1b1a76978ae39ce93aadcf4859d9eb1d55605694

diff --git a/client/src/com/vaadin/client/data/AbstractRemoteDataSource.java b/client/src/com/vaadin/client/data/AbstractRemoteDataSource.java
index bda923ef6fdd18285ab022132792e1225acb71e4..ff8847ea446bd56e858678640cba1537a1077727 100644 (file)
--- a/client/src/com/vaadin/client/data/AbstractRemoteDataSource.java
+++ b/client/src/com/vaadin/client/data/AbstractRemoteDataSource.java
@@ -210,7 +210,16 @@ public abstract class AbstractRemoteDataSource<T> implements DataSource<T> {
                 cached = newUsefulData;
             } else {
                 discardStaleCacheEntries();
-                cached = cached.combineWith(newUsefulData);
+
+                /*
+                 * everything might've become stale so we need to re-check for
+                 * emptiness.
+                 */
+                if (!cached.isEmpty()) {
+                    cached = cached.combineWith(newUsefulData);
+                } else {
+                    cached = newUsefulData;
+                }
             }
         }