[Maken]

It is indeed a typo, and my guess is that the author tried to avoid an ambiguity in the parser there.

In Spanish "else" would be "si no", which is literally "if not". Assuming he supports negating any boolean expression with "no", this means the only way to differentiate between "else" and "if not <expression>" is to parse ahead and check if "si no" is being followed by a boolean expression or literally anything else. Also, under these conditions, assigning a boolean at the end of a conditional, e.g. "si no foo = falso", would always result in a parsing error.