Fixed NPE warnings (#127)

Author: alex268

jdbc/src/main/java/tech/ydb/jdbc/context/YdbContext.java

@@ -429,9 +429,10 @@ public YdbPreparedQuery findOrPrepareParams(YdbQuery query, YdbPrepareMode mode)
         }
 
         QueryType type = query.getType();
+        YqlBatcher batcher = query.getYqlBatcher();
 
         if (type == QueryType.BULK_QUERY) {
-            if (query.getYqlBatcher() == null || query.getYqlBatcher().getCommand() != YqlBatcher.Cmd.UPSERT) {
+            if (batcher == null || batcher.getCommand() != YqlBatcher.Cmd.UPSERT) {
                 throw new SQLException(YdbConst.BULKS_UNSUPPORTED);
             }
         }
@@ -441,8 +442,8 @@ public YdbPreparedQuery findOrPrepareParams(YdbQuery query, YdbPrepareMode mode)
             return new InMemoryQuery(query, queryOptions.isDeclareJdbcParameters());
         }
 
-        if (query.getYqlBatcher() != null && (mode == YdbPrepareMode.AUTO || type == QueryType.BULK_QUERY)) {
-            String tablePath = joined(getPrefixPath(), query.getYqlBatcher().getTableName());
+        if (batcher != null && (mode == YdbPrepareMode.AUTO || type == QueryType.BULK_QUERY)) {
+            String tablePath = joined(getPrefixPath(), batcher.getTableName());
             TableDescription description = tableDescribeCache.getIfPresent(tablePath);
             if (description == null) {
                 YdbTracer tracer = getTracer();
@@ -469,7 +470,7 @@ public YdbPreparedQuery findOrPrepareParams(YdbQuery query, YdbPrepareMode mode)
                 if (query.getReturning() != null) {
                     throw new SQLException(YdbConst.BULK_NOT_SUPPORT_RETURNING);
                 }
-                return BulkUpsertQuery.build(types, tablePath, query.getYqlBatcher().getColumns(), description);
+                return BulkUpsertQuery.build(types, tablePath, batcher.getColumns(), description);
             }
 
             if (description != null) {

jdbc/src/main/java/tech/ydb/jdbc/impl/BaseYdbResultSet.java

@@ -93,7 +93,7 @@ private ValueReader readValue(int columnIndex) throws SQLException {
 
         ValueReader value = getValue(columnIndex - 1);
         ColumnInfo type = columns[columnIndex - 1];
-        wasNull = type.isNull() || (type.isOptional() && !value.isOptionalItemPresent());
+        wasNull = type == null || type.isNull() || (type.isOptional() && !value.isOptionalItemPresent());
         return value;
     }
 
@@ -594,10 +594,10 @@ public Value<?> getNativeColumn(int columnIndex) throws SQLException {
         if (wasNull) {
             return null;
         }
-        while (value.getType().getKind() == Type.Kind.OPTIONAL) {
+        while (value != null && value.getType().getKind() == Type.Kind.OPTIONAL) {
             value = value.getOptionalItem();
         }
-        return value.getValue();
+        return value == null ? null : value.getValue();
     }
 
     @Override

jdbc/src/main/java/tech/ydb/jdbc/query/params/BatchedQuery.java

@@ -234,6 +234,9 @@ public static BatchedQuery createAutoBatched(YdbTypes types, YdbQuery query, Tab
             throws SQLException {
 
         YqlBatcher batcher = query.getYqlBatcher();
+        if (batcher == null) {
+            return null;
+        }
 
         // DELETE and UPDATE may be batched only if WHERE contains only primary key columns
         if (batcher.getCommand() == YqlBatcher.Cmd.DELETE || batcher.getCommand() == YqlBatcher.Cmd.UPDATE) {