ERGM crashes when fitting MCMC: "Error in T2nullity && verbose : invalid 'x' type in 'x && y'"

[matwurst]

Dear all,

I will keep it short since it's late at night, but every time my models start to fit the model, it crashes with the following error:

Iteration 16 of at most 60:
Optimizing with step length 1.0000.
The log-likelihood improved by 0.0826.
Error in T2nullity && verbose : invalid 'x' type in 'x && y'

anyone has an idea where this comes from?

This is my code:

model <- ergm(mixed.recht ~ edges + +gwesp(0.25,fixed=T) + nodefactor("student") + ...)

[mbojan]

Locking this since an identical issue #503 is filed.