5.2.2. Solution

Use:

if (12 == $dwarves) { ... }

instead of:

if ($dwarves == 12) { ... }

Putting the constant on the left triggers a parse error with the assignment operator. In other words, PHP complains when you write:

if (12 = $dwarves) { ... }

but:

if ($dwarves = 12) { ... }

silently executes, assigning 12 to the variable $dwarves, and then executing the code inside the block. ($dwarves = 12 evaluates to 12, which is true.)