[Fix]fix insert overwrite non-partition table null pointer exception (#33205)

fix legacy planner bug when insert overwrite non-partition table.

fe/fe-core/src/main/java/org/apache/doris/qe/StmtExecutor.java

@@ -2602,6 +2602,9 @@ public class StmtExecutor {
             if (iotStmt.getPartitionNames().size() == 0) {
                 // insert overwrite table
                 handleOverwriteTable(iotStmt);
+            } else if (iotStmt.isAutoDetectPartition()) {
+                // insert overwrite table auto detect which partitions need to replace
+                handleAutoOverwritePartition(iotStmt);
             } else {
                 // insert overwrite table with partition
                 handleOverwritePartition(iotStmt);

regression-test/suites/insert_overwrite_p0/insert_overwrite_legacy_unpartitioned.groovy

@@ -0,0 +1,31 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+suite("insert_overwrite_legacy_unpartitioned") {
+    sql "drop table if exists test_no_partition_insert"
+    sql """
+        create table test_no_partition_insert (a int, b int)
+        duplicate key(a)
+        distributed by hash(a) buckets 32
+        properties(
+            "replication_allocation"="tag.location.default: 1"
+        );
+    """
+
+    sql """insert overwrite table test_no_partition_insert
+        select 1,2 from test_no_partition_insert minus select 1,2 from test_no_partition_insert;"""
+}