Unless you can find an actual, paid job, take the volunteer position. There are plenty of reasons to do so:
1. It'll look better on your record than just sitting at home, so it'll be make finding a job more likely, even if just a little bit.
2. When someone (as in a neighbor or something) asks you what you do, you can say you work at a library. You work for free, yes, but they won't know that unless they ask how much you earn.
3. It'll keep you from forgetting how to handle that kind of job and how to stay in a routine of a working person.
4. If you prove yourselve to be useful and they need more staff, the chances that they'd rather hire you than use time to teach the rules and ways of that particular place to someone new are high.
This more or less happened to me. In Decemeber 2017, I entered this training program for a month. I didn't feel like I needed it, but I knew it'd look better on my record than being at home, so I went. After the first month, I was asked if I'd do two more. Before that I'd been unemployed for rather long and I only did 16 hours a week in the training program, so I thought why not since I hadn't gotten bored yet. From the start they'd made it clear they wouldn't hire anyone new, yet when my two months was almost up I was asked if I'd like to work for them. Being unemployed, I said yes of course despite the position being part time and only with a short contract. I'm still at the same place, having gotten few new short contracts. The point is that despite saying that they won't hire anyone, they still did. My guess is that they said it because they didn't want to have any pressure to hire me in case I turned out to be too lazy or sloppy worker. So even if they say at the volunteer position that no one will be hired, do your job as well as possible. It just might pay off.
And hey, it's not impossible to get a job despite those things. I've been unemployed for long time periods, have education for a career that is rapidly losing jobs, have a physical disability on top of my autism yet I'm still working. Disabilities slow people down, but they don't always block the entire way. 