Disallow evaluating at empty vectors

Author: SoongNoonien

src/generic/UnivPoly.jl

@@ -788,10 +788,10 @@ end
 ###############################################################################
 
 function evaluate(a::UnivPoly, A::Vector{<:Union{NCRingElem, RingElement}})
+   isempty(A) && error("Too few values")
    a2 = data(a)
    varidx = Int[var_index(x) for x in vars(a2)]
    isempty(varidx) && return constant_coefficient(a2)
-   isempty(A) && error("Number of variables does not match number of values")
    vals = zeros(parent(A[1]), nvars(parent(a2)))
    n = length(A)
    for i in varidx