Fix OffsetOperatorTest null TsBlock handling

Author: Caideyipi

iotdb-core/datanode/src/test/java/org/apache/iotdb/db/queryengine/execution/operator/OffsetOperatorTest.java

@@ -169,6 +169,9 @@ public void batchTest1() throws Exception {
       int count = 100;
       while (limitOperator.isBlocked().isDone() && limitOperator.hasNext()) {
         TsBlock tsBlock = limitOperator.next();
+        if (tsBlock == null) {
+          continue;
+        }
         assertEquals(2, tsBlock.getValueColumnCount());
         assertTrue(tsBlock.getColumn(0) instanceof IntColumn);
         assertTrue(tsBlock.getColumn(1) instanceof IntColumn);
@@ -277,6 +280,9 @@ public void batchTest2() throws Exception {
       int count = 0;
       while (offsetOperator.isBlocked().isDone() && offsetOperator.hasNext()) {
         TsBlock tsBlock = offsetOperator.next();
+        if (tsBlock == null) {
+          continue;
+        }
         assertEquals(2, tsBlock.getValueColumnCount());
         assertTrue(tsBlock.getColumn(0) instanceof IntColumn);
         assertTrue(tsBlock.getColumn(1) instanceof IntColumn);
@@ -383,6 +389,9 @@ public void batchTest3() throws Exception {
 
       while (offsetOperator.isBlocked().isDone() && offsetOperator.hasNext()) {
         TsBlock tsBlock = offsetOperator.next();
+        if (tsBlock == null) {
+          continue;
+        }
         assertEquals(2, tsBlock.getValueColumnCount());
         assertTrue(tsBlock.getColumn(0) instanceof IntColumn);
         assertTrue(tsBlock.getColumn(1) instanceof IntColumn);
@@ -475,6 +484,9 @@ public void batchTest4() throws Exception {
 
       while (offsetOperator.isBlocked().isDone() && offsetOperator.hasNext()) {
         TsBlock tsBlock = offsetOperator.next();
+        if (tsBlock == null) {
+          continue;
+        }
         assertEquals(2, tsBlock.getValueColumnCount());
         assertTrue(tsBlock.getColumn(0) instanceof IntColumn);
         assertTrue(tsBlock.getColumn(1) instanceof IntColumn);