overflow error when using the chorus filter/effect

[Jeff Fortin Tam]

To reproduce with jokosher trunk:
1- load an audio file (in my case, just some pop music, "Stereo Flo")
2- start playback
3- go in the filters dialog, add a chorus filter
4- configure the filter, and raise the number of voices above 1

The following traceback will be constantly printed:

Traceback (most recent call last):
  File "/home/jeff/trunks/jokosher/Jokosher/Project.py", line 683, in __PipelineBusLevelCb
    instr.SetLevel(Utils.DbToFloat(struct["decay"][0]))
  File "/home/jeff/trunks/jokosher/Jokosher/Utils.py", line 108, in DbToFloat
    return pow(10., f / 20.)
OverflowError: (34, 'Numerical result out of range')