代码自动生成工具，当表注释为空时，根据SQL导入失败问题修复

yudao-admin-server/src/main/java/cn/iocoder/yudao/adminserver/modules/tool/service/codegen/impl/ToolCodegenSQLParser.java

@@ -64,10 +64,17 @@ public class ToolCodegenSQLParser {
     private static ToolSchemaTableDO parseTable(SQLCreateTableStatement statement) {
         return ToolSchemaTableDO.builder()
                 .tableName(statement.getTableSource().getTableName(true))
-                .tableComment(((SQLCharExpr) statement.getComment()).getText())
+                .tableComment(getCommentText(statement))
                 .build();
     }
 
+    private static String getCommentText(SQLCreateTableStatement statement) {
+        if (statement == null || statement.getComment() == null) {
+            return "";
+        }
+        return ((SQLCharExpr) statement.getComment()).getText();
+    }
+
     private static List<ToolSchemaColumnDO> parseColumns(SQLCreateTableStatement statement) {
         List<ToolSchemaColumnDO> columns = new ArrayList<>();
         statement.getTableElementList().forEach(element -> parseColumn(columns, element));