Always reproduced:

```
milovidov-desktop :) create table table_map (a Map(String, String), b String) engine = MergeTree() order by a;

CREATE TABLE table_map
(
    `a` Map(String, String),
    `b` String
)
ENGINE = MergeTree
ORDER BY a

Query id: 8f8120c1-c165-452a-815f-2bcae3957e2a

Ok.

0 rows in set. Elapsed: 0.002 sec. 

milovidov-desktop :) SELECT b FROM table_map WHERE a = map('name', NULL, '', NULL)

SELECT b
FROM table_map
WHERE a = {'name', NULL, '', NULL}
```
{
        
        if (checkAndGetDataType<DataTypeString>(from_type_untyped.get()))
        {
            return [] (ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, const ColumnNullable *, size_t )
            {
                return ConvertImplGenericFromString::execute(arguments, result_type);
            };
        }
        else
        {
            if (cast_type == CastType::accurateOrNull)
                return createToNullableColumnWrapper();
            else
                throw Exception{"Conversion from " + from_type_untyped->getName() + " to " + to_type->getName() +
                    " is not supported", ErrorCodes::CANNOT_CONVERT_TYPE};
        }
    }
    WrapperType createArrayWrapper(const DataTypePtr & from_type_untyped, const DataTypeArray * to_type) const