```
SELECT version()
─version()─┐
│ 21.8.5.7  │
└───────────┘
```
We have a request, as a result of which we get an array.
When getting an item using a computed value, there is no value
```
SELECT
    arrayMap(x -> x, [[1], [2], [3]]) AS x,
    toTypeName(x),
    x[3 - 2] AS y,
    x[toInt64(1)] AS yy,
    x[toUInt8(1)] AS yyy

┌─x─────────────┬─toTypeName(arrayMap(lambda(tuple(x), x), [[1], [2], [3]]))─┬─y──┬─yy─┬─yyy─┐
│ [[1],[2],[3]] │ Array(Array(UInt8))                                        │ [] │ [] │ [1] │
└───────────────┴────────────────────────────────────────────────────────────┴────┴────┴─────┘
```
However, when the array is explicitly specified, the value is present.
The types are the same.
```
SELECT
    [[1], [2], [3]] AS x,
    toTypeName(x),
    x[3 - 2] AS y,
    x[toInt64(1)] AS yy,
    x[toInt8(1)] AS yyy

┌─x─────────────┬─toTypeName([[1], [2], [3]])─┬─y───┬─yy──┬─yyy─┐
│ [[1],[2],[3]] │ Array(Array(UInt8))         │ [1] │ [1] │ [1] │
└───────────────┴─────────────────────────────┴─────┴─────┴─────┘
```


ColumnArray::create(nested_col, col_array->getOffsetsPtr()),
                    std::make_shared<DataTypeArray>(input_type),
                    ""
                },
                arguments[1],
            };
            builder.initSource(nullable_col.getNullMapData().data());
        }
        else
        {
            
            const auto & nullable_col = assert_cast<const ColumnNullable &>(col_const_array->getData());
            const auto & nested_col = nullable_col.getNestedColumnPtr();
            source_columns =
            {
                {
                    ColumnConst::create(ColumnArray::create(nested_col, col_const_array->getOffsetsPtr()), input_rows_count),
                    std::make_shared<DataTypeArray>(input_type),
                    ""
                },
                arguments[1],
            };
            builder.initSource(nullable_col.getNullMapData().data());
        }
        auto res = perform(source_columns, tmp_ret_type, builder, input_rows_count);
        
        return ColumnNullable::create(res, builder ? std::move(builder).getNullMapColumnPtr() : ColumnUInt8::create());
    }
}
ColumnPtr FunctionArrayElement::perform(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type,