IndexError if unsupported parameter is used

[twodrops]

If a wrong parameter is (accidently) passed to sphinx-performance, the following IndexError is raised

IndexError: list index out of range

[danwos]

Interesting, there should not be any wrong parameters, as sphinx-performance takes any name and number of it.
It depends on the used test project if these parameters get used or are ignored.

But for sure it's a bug. will take a look.