Reproduction steps:
```
CREATE TABLE table_left                                                                                                                                                                                              
(                                                                                                                                                                                                                    
    `date` Date,                                                                                                                                                                                                     
    `uid` String                                                                                                                                                                                                     
)                                                                                                                                                                                                                    
ENGINE = MergeTree()                                                                                                                                                                                                 
ORDER BY (date, uid)          
                                                                                                                                                                                       
CREATE TABLE table_right                                                                                                                                                                                             
(                                                                                                                                                                                                                    
    `date` Date,                                                                                                                                                                                                     
    `value` Decimal(18, 10)                                                                                                                                                                                          
)                                                                                                                                                                                                                    
ENGINE = MergeTree()                                                                                                                                                                                                 
ORDER BY date

INSERT INTO table_left values(toDate('2019-10-01'), 'hello');
INSERT INTO table_right values (toDate('2019-10-01'), 1), (toDate('2029-10-01'), 2);

SET join_use_nulls = 1;

SELECT ifNull(subquery_right.alias_value, 0)
FROM table_left
FULL OUTER JOIN 
(
    SELECT
        date,
        value AS alias_value
    FROM table_right
) AS subquery_right
ON table_left.date = subquery_right.date

Received exception from server (version 21.3.1):
Code: 43. DB::Exception: Received from localhost:9000. DB::Exception: Incompatible types of arguments corresponding to two conditional branches: while executing 'FUNCTION ifNull(alias_value :: 0, 0 :: 1) -> ifNull(alias_value, 0) Decimal(18, 10) : 2'. 
```
[[maybe_unused]] const ColumnUInt8 * cond_col,
        [[maybe_unused]] const ColumnsWithTypeAndName & arguments,
        [[maybe_unused]] const DataTypePtr & result_type,
        [[maybe_unused]] const ColumnConst * col_left_const_array,
        [[maybe_unused]] size_t input_rows_count) const
    {
        if constexpr (std::is_same_v<NumberTraits::Error, typename NumberTraits::ResultOfIf<T0, T1>::Type>)
            return nullptr;
        else
        {
            using ResultType = typename NumberTraits::ResultOfIf<T0, T1>::Type;
            const IColumn * col_right_untyped = arguments[2].column.get();
            if (const auto * col_right_array = checkAndGetColumn<ColumnArray>(col_right_untyped))
            {
                const ColVecT1 * col_right_vec = checkAndGetColumn<ColVecT1>(&col_right_array->getData());
                if (!col_right_vec)
                    return nullptr;
                auto res = result_type->createColumn();
                auto & arr_res = assert_cast<ColumnArray &>(*res);
                conditional(
                    ConstSource<NumericArraySource<T0>>(*col_left_const_array),
                    NumericArraySource<T1>(*col_right_array),
                    NumericArraySink<ResultType>(arr_res.getData(), arr_res.getOffsets(), input_rows_count),
                    cond_col->getData());
                return res;
            }
            else if (const auto * col_right_const_array = checkAndGetColumnConst<ColumnArray>(col_right_untyped))
            {