Double negative

Question

Instead of using the 'double negative' in "espero que no haya ningún accidente porque si no ..." - could we also say: "espero que no haya ningún accidente porque si lo hay, será peor"? - i.e., arguing that it sounds clearer to word it as: "I hope that there is no accident, because if there is [one] then it will be [even] worse"...  In English, certainly, some thought would be necessary in order to work out the meaning of: "I hope that there is no accident, because if not then it will be [even] worse". I suppose this is really just a 'matter of taste' -[in both languages? - I have the impression that double negatives are a complicated topic in Spanish].

Accepted Answer

Hola David
It's very interesting that you brought this up, actually. I can see why that "porque si no..." is so difficult to see. This is actually quite idiomatic for a "because otherwise...". What we do here is kind of omit part of the sentence, so it is as if we said: 
Espero que no haya ningún accidente porque si no fuera de este modo [i.e. not having any accident], sería peor.
When we shorten it or simply use the expression "porque si no", we can't really see the whole thing and it sounds odd to use a "no" there. 
I'll give you some other sentences in other contexts where you can use the same:

Estás castigado, así que no salgas de tu habitación, porque si no, no saldrás de casa en un mes.
You're grounded, so, don't leave your room, because otherwise (if you don't do what I say), you won't leave the house in a month.  
 
Creo que no voy a decirle nada a mi marido porque si no, seguro que se pone celoso.
I don't think I'll tell my husband anything because otherwise, I'm sure he'll get all jealous.
 
No seas tan traviesa, porque si no, los Reyes Magos no te van a traer regalos.
Don't be so naughty, because otherwise the Wise Men won't bring you any presents.

You can see in these other sentences that we still use the "no" but there is no obvious need to do so. We see "porque si no" as a standalone expression to say "because otherwise", both in affirmative and negative sentences. 
I hope this clarifies your doubt about this option that we use in the writing challenge. 
Nevertheless, your option using "porque si lo hay..." is also a very valid alternative, so that will be included in the exercise shortly. 
Gracias y felices fiestas para ti y tu familia.
Inma

Answer

Thank you Inma - I really appreciate your detailed reply: it will certainly help me remember "porque si no ..." as an important idiomatic construction.

I would like to wish you and everybody else at Kwiziq: All the very best for 2023 !

Answer

Hola DavidGracias y ¡Feliz 2023 para ti también de todos los de Kwiziq!: ))