Running examples in ‘ergm.multi-Ex.R’ failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: gofN
> ### Title: Linear model diagnostics for multinetwork linear models
> ### Aliases: gofN [.gofN augment.gofN summary.gofN
> 
> ### ** Examples
> 
> data(samplk)
> monks <- Networks(samplk1, samplk2, samplk3,samplk1, samplk2, samplk3,samplk1, samplk2, samplk3)
> fit <- ergm(monks~N(~edges+nodematch("group")))
Starting maximum pseudolikelihood estimation (MPLE):
Obtaining the responsible dyads.
Evaluating the predictor and response matrix.
Maximizing the pseudolikelihood.
Finished MPLE.
Evaluating log-likelihood at the estimate. 
> fit.gof <- gofN(fit) # GOF = original model
Constructing simulation model(s).
Constructing GOF model.
Simulating unconstrained sample.
Collating the simulations.
Summarizing.
> summary(fit.gof)
$`Observed/Imputed values`
   N(1)~edges N(1)~nodematch.group
 Min.   :55   Min.   :30.00       
 1st Qu.:55   1st Qu.:30.00       
 Median :56   Median :38.00       
 Mean   :56   Mean   :35.33       
 3rd Qu.:57   3rd Qu.:38.00       
 Max.   :57   Max.   :38.00       

$`Fitted values`
   N(1)~edges    N(1)~nodematch.group
 Min.   :54.17   Min.   :34.41       
 1st Qu.:55.05   1st Qu.:34.66       
 Median :56.02   Median :34.94       
 Mean   :55.92   Mean   :35.05       
 3rd Qu.:56.69   3rd Qu.:35.43       
 Max.   :57.27   Max.   :36.10       

$`Pearson residuals`
   N(1)~edges       N(1)~nodematch.group
 Min.   :-0.32426   Min.   :-1.2761     
 1st Qu.:-0.01279   1st Qu.:-1.0294     
 Median : 0.03327   Median : 0.6691     
 Mean   : 0.02269   Mean   : 0.1230     
 3rd Qu.: 0.13794   3rd Qu.: 0.7488     
 Max.   : 0.20473   Max.   : 1.0209     

$`Variance of Pearson residuals`
$`Variance of Pearson residuals`$`N(1)~edges`
[1] 0.02831001

$`Variance of Pearson residuals`$`N(1)~nodematch.group`
[1] 0.9245554


$`Std. dev. of Pearson residuals`
$`Std. dev. of Pearson residuals`$`N(1)~edges`
[1] 0.1682558

$`Std. dev. of Pearson residuals`$`N(1)~nodematch.group`
[1] 0.961538


> plot(fit.gof)
Warning in rep(a, length.out = np) :
  'x' is NULL so the result will be NULL
Error in title(...) : 
  conversion failure on 'Residuals vs. Fitted for ‘N(1)~edges’' in 'mbcsToSbcs': for ‘
Calls: plot ... resid.plotter -> plot -> plot.default -> localTitle -> title
Execution halted