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}
```
UInt32 scale { 0 };
};
struct ConvertDefaultBehaviorTag {};
struct ConvertReturnNullOnErrorTag {};
/** Conversion of number types to each other, enums to numbers, dates and datetimes to numbers and back: done by straight assignment.
  *  (Date is represented internally as number of days from some day; DateTime - as unix timestamp)
  */
template <typename FromDataType, typename ToDataType, typename Name, typename SpecialTag = ConvertDefaultBehaviorTag>
struct ConvertImpl
{
    using FromFieldType = typename FromDataType::FieldType;
    using ToFieldType = typename ToDataType::FieldType;
    template <typename Additions = void *>
    static ColumnPtr NO_SANITIZE_UNDEFINED execute(
        const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type [[maybe_unused]], size_t ,
        Additions additions [[maybe_unused]] = Additions())
    {
        const ColumnWithTypeAndName & named_from = arguments[0];
        using ColVecFrom = typename FromDataType::ColumnType;
        using ColVecTo = typename ToDataType::ColumnType;
        if (std::is_same_v<Name, NameToUnixTimestamp>)
        {
            if (isDate(named_from.type))
                throw Exception("Illegal type " + named_from.type->getName() + " of first argument of function " + Name::name,
                    ErrorCodes::ILLEGAL_COLUMN);
        }
        if constexpr ((IsDataTypeDecimal<FromDataType> || IsDataTypeDecimal<ToDataType>)
            && !(std::is_same_v<DataTypeDateTime64, FromDataType> || std::is_same_v<DataTypeDateTime64, ToDataType>))
        {
            if constexpr (!IsDataTypeDecimalOrNumber<FromDataType> || !IsDataTypeDecimalOrNumber<ToDataType>)