Question: Why do I get error messages such as "LessEqual::nord: Invalid comparison with 1. -1.59148 I attempted." when I try to plot the function f[z,k] defined below with for example the Plot invocation illustrated below?

f[z_, k_] := (
 I E^(-((2 I \[Pi])/k))
   HurwitzLerchPhi[E^(-((2 I \[Pi])/k)), 1, 1 + (I z)/(2 \[Pi])])/(
 2 \[Pi])

Plot[{Abs@f[s, 2]}, {s, -10, 10}, GridLines -> Automatic]