[Bug] O / PP parameters with a non-int value cause a 500
**Reported by `mpan` on IRC**
- [x] I have described the bug in complete detail in the
[Description](#description) section.
- [x] I have specified steps in the [Reproduction](#reproduction) section.
- [x] I have included the versions which are affected in the
[Version(s)](#versions) section.
### Description
When passing a non-int value to the O or PP parameters for package search or the requests page, a 500 Internal Server error is returned.
### Reproduction
Visit `/packages?O=0&SeB=nd&K=%25test&outdated=&SB=n&SO=a&PP=1%20or%201&submit=Go`, which uses a "1 or 1" string as the PP parameter.
### Version(s)
8dcdc7ff38fcf21434ef79045db7621891d02d74
issue