#4805 taylor bad error message

[Barton Willis]

I'm not sure what taylor should do for this case--should it ask about the relative magnitudes of a and b. But to a user, the error message is meaningless:

(%i4) xxx : (a^x + b^x)^(1/x);

(%o4) (b^x+a^x)^(1/x)
(%i5) taylor(%,x,inf, 1);
taylor: bad gvar lim
infinity
 -- an error. To debug this try: debugmode(true);