  The Keller-Segel equations are widely used for describing chemotaxis in
biology. Recently, a new fully discrete scheme for this model was proposed in
[46], mass conservation, positivity and energy decay were proved for the
proposed scheme, which are important properties of the original system. In this
paper, we establish the error estimates of this scheme. Then, based on the
error estimates, we derive the finite-time blowup of nonradial numerical
solutions under some conditions on the mass and the moment of the initial data.
