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}
```
{
        const auto & col_with_type_and_name = arguments[0];
        const IDataType & type = *col_with_type_and_name.type;
        const IColumn & col_from = *col_with_type_and_name.column;
        size_t size = col_from.size();
        auto col_to = ColumnString::create();
        ColumnString::Chars & data_to = col_to->getChars();
        ColumnString::Offsets & offsets_to = col_to->getOffsets();
        data_to.resize(size * 2); 
        offsets_to.resize(size);
        WriteBufferFromVector<ColumnString::Chars> write_buffer(data_to);
        FormatSettings format_settings;
        auto serialization = type.getDefaultSerialization();
        for (size_t i = 0; i < size; ++i)
        {
            serialization->serializeText(col_from, i, write_buffer, format_settings);
            writeChar(0, write_buffer);
            offsets_to[i] = write_buffer.count();
        }
        write_buffer.finalize();
        return col_to;
    }
};
/** Conversion of strings to numbers, dates, datetimes: through parsing.
  */
template <typename DataType>
void parseImpl(typename DataType::FieldType & x, ReadBuffer & rb, const DateLUTImpl *)