[Numpy-discussion] Correct error of invalid axis arguments.

Hi All, At the moment there are two error types raised when invalid axis arguments are encountered: IndexError and ValueError. I prefer ValueError for arguments, IndexError seems more appropriate when the bad axis value is used as an index. In any case, having mixed error types is inconvenient, but also inconvenient to change. Should we worry about that? If so, what should the error be? Note that some of the mixup arises because the axis values are not checked before use, in which case IndexError is raised. Chuck