\label{fig:crosserr}
Uncertainty on the form factors at the FCC-ee with 2.4\,${\rm ab}^{-1}$ at $\sqrt{s} = 365$\,GeV, as a function of the relative cross-section theorerical error, varied from 0.01\% to 100\%. Left column, from top to bottom: $F_{1V}^\gamma$, $F_{1V}^Z$, and $F_{1A}^Z$. Right column: $F_{2V}^\gamma$ and $F_{2V}^Z$.