Updating a Nullable column value by using alter .... where ... causes to set another value!

ClickHouse version: 20.6.3.28
Engine: MergeTree
OS: Ubuntu 18.04.3 LTS

Steps to reproduce:
```sql
CREATE TABLE table1(
	id int,
	price Nullable(Int32)
)
ENGINE = MergeTree()
PARTITION BY id
ORDER BY (id);
INSERT INTO table1 (id, price) VALUES (1, 100);
ALTER TABLE table1  update price = 150 where id=1;
SELECT * FROM table1;
```
We expect the price to be `150`, but it's `93148480`:

```
┌─id─┬────price─┐
│  1 │ 93148480 │
└────┴──────────┘
```
Using `Decimal(9,2)` field instead of `Int32` would set the value  `932342.88` always. It seems there's a fixed value for each data type.

If we don't use such a `where` clause, it works correctly:
```sql
ALTER TABLE db1.table1  update price = 150 where 1=1;
┌─id─┬─price─┐
│  1 │   150 │
└────┴───────┘
```
{
public:
    static constexpr auto name = "if";
    static FunctionPtr create(const Context &) { return std::make_shared<FunctionIf>(); }
private:
    template <typename T0, typename T1>
    static UInt32 decimalScale(Block & block [[maybe_unused]], const ColumnNumbers & arguments [[maybe_unused]])
    {
        if constexpr (IsDecimalNumber<T0> && IsDecimalNumber<T1>)
        {
            UInt32 left_scale = getDecimalScale(*block.getByPosition(arguments[1]).type);
            UInt32 right_scale = getDecimalScale(*block.getByPosition(arguments[2]).type);
            if (left_scale != right_scale)
                throw Exception("Conditional functions with different Decimal scales", ErrorCodes::NOT_IMPLEMENTED);
            return left_scale;
        }
        else
            return std::numeric_limits<UInt32>::max();
    }
    template <typename T0, typename T1, typename ColVecT0, typename ColVecT1>
    bool executeRightType(