fix: preceding simple statement in IfStmt should have its own block

[shenyih0ng]

Description

Right now the ECE fails the following test case:

func main() {
    var i = 26
    
    if i := 25; i % 3 == 0 && i % 5 == 0 {
        println("FizzBuzz")
    } else if i % 3 == 0 {
        println("Fizz")
    } else if i % 5 == 0 {
        println(i) // 25 
        println("Buzz") // Buzz
    }
    
    println(i) // 26
}

This is because the declaration i:=25 incorrectly reassigns the i in the scope of main. The fix is to surround the if statement with a block if there is a preceding statement