**Use case**

```
Received exception from server (version 21.11.1):
Code: 36. DB::Exception: Received from localhost:9000. DB::Exception: Wrong index name. Cannot find index `test_pentagram` to drop.. (BAD_ARGUMENTS)

github-explorer.ru-central1.internal :) ALTER TABLE hackernews DROP INDEX text_pentagram
```

It did not show me the typo.
command.if_not_exists = command_ast->if_not_exists;
        return command;
    }
    else if (command_ast->type == ASTAlterCommand::ADD_PROJECTION)
    {
        AlterCommand command;
        command.ast = command_ast->clone();
        command.projection_decl = command_ast->projection_decl;
        command.type = AlterCommand::ADD_PROJECTION;
        const auto & ast_projection_decl = command_ast->projection_decl->as<ASTProjectionDeclaration &>();
        command.projection_name = ast_projection_decl.name;
        if (command_ast->projection)
            command.after_projection_name = command_ast->projection->as<ASTIdentifier &>().name();
        command.first = command_ast->first;
        command.if_not_exists = command_ast->if_not_exists;
        return command;
    }
    else if (command_ast->type == ASTAlterCommand::DROP_CONSTRAINT)
    {
        AlterCommand command;
        command.ast = command_ast->clone();
        command.if_exists = command_ast->if_exists;
        command.type = AlterCommand::DROP_CONSTRAINT;
        command.constraint_name = command_ast->constraint->as<ASTIdentifier &>().name();
        return command;
    }
    else if (command_ast->type == ASTAlterCommand::DROP_INDEX)
    {
        AlterCommand command;
        command.ast = command_ast->clone();