For example, if I use UInt8 constant for if condition then only one branch is evaluated:
```sql
SELECT if(1, 'success', throwIf(1, 'Executing FALSE branch'))

┌─'success'─┐
│ success   │
└───────────┘

1 rows in set. Elapsed: 0.003 sec.
```

But if I use some constant expression, then both branches are evaluated:
```sql
SELECT if(empty(''), 'success', throwIf(1, 'Executing FALSE branch'))

0 rows in set. Elapsed: 0.003 sec.

Received exception from server (version 21.12.2):
Code: 395. DB::Exception: Received from localhost:9000. DB::Exception: Executing FALSE branch: While processing if(empty(''), 'success', throwIf(1, 'Executing FALSE branch')). (FUNCTION_THROW_IF_VALUE_IS_NON_ZERO)
```
? else_is_nullable->getNullMapColumnPtr()
                        : DataTypeUInt8().createColumnConstWithDefaultValue(input_rows_count),
                    std::make_shared<DataTypeUInt8>(),
                    ""
                }
            });
            result_null_mask = executeImpl(temporary_columns, std::make_shared<DataTypeUInt8>(), input_rows_count);
        }
        ColumnPtr result_nested_column;
        {
            ColumnsWithTypeAndName temporary_columns(
            {
                arg_cond,
                {
                    recursiveGetNestedColumnWithoutNullable(arg_then.column),
                    removeNullable(arg_then.type),
                    ""
                },
                {
                    recursiveGetNestedColumnWithoutNullable(arg_else.column),
                    removeNullable(arg_else.type),
                    ""
                }
            });
            result_nested_column = executeImpl(temporary_columns, removeNullable(result_type), temporary_columns.front().column->size());
        }
        return ColumnNullable::create(
            materializeColumnIfConst(result_nested_column), materializeColumnIfConst(result_null_mask));
    }
    ColumnPtr executeForNullThenElse(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const