Avoid null pointer exceptions from empty tables without snapshot

Author: raunaqmorarka

plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java

@@ -3423,6 +3423,9 @@ else if (isMetadataColumnId(columnHandle.getId())) {
 
     private static List<ManifestFile> loadAllManifestsFromSnapshot(Table icebergTable, Snapshot snapshot)
     {
+        if (snapshot == null) {
+            return ImmutableList.of();
+        }
         try {
             return snapshot.allManifests(icebergTable.io());
         }