Return null in BigQuery getNextSourcePage

Author: ebyhr

plugin/trino-bigquery/src/main/java/io/trino/plugin/bigquery/BigQueryQueryPageSource.java

@@ -161,6 +161,9 @@ public long getMemoryUsage()
     public SourcePage getNextSourcePage()
     {
         verify(pageBuilder.isEmpty());
+        if (!tableResultFuture.isDone()) {
+            return null;
+        }
         if (tableResult == null) {
             tableResult = getFutureValue(tableResultFuture);
         }

plugin/trino-bigquery/src/main/java/io/trino/plugin/bigquery/BigQueryStorageArrowPageSource.java

@@ -106,6 +106,9 @@ public boolean isFinished()
     public SourcePage getNextSourcePage()
     {
         checkState(pageBuilder.isEmpty(), "PageBuilder is not empty at the beginning of a new page");
+        if (!nextResponse.isDone()) {
+            return null;
+        }
         ReadRowsResponse response;
         try {
             response = getFutureValue(nextResponse);

plugin/trino-bigquery/src/main/java/io/trino/plugin/bigquery/BigQueryStorageAvroPageSource.java

@@ -159,6 +159,9 @@ public boolean isFinished()
     public SourcePage getNextSourcePage()
     {
         checkState(pageBuilder.isEmpty(), "PageBuilder is not empty at the beginning of a new page");
+        if (!nextResponse.isDone()) {
+            return null;
+        }
         ReadRowsResponse response;
         try {
             response = getFutureValue(nextResponse);