Skip failed calculations

[yutannihilation]

Fix #70 (and #66)

library(gghighlight)
#> Loading required package: ggplot2
library(glmnetUtils)
library(ggfortify)

model <- glmnet(medv ~ ., data = MASS::Boston)

autoplot(model, xvar = "lambda") +
  gghighlight(variable == "crim", use_group_by = FALSE)
#> Warning: Could not calculate the predicate for layer 2; ignored
#> label_key: variable

^{Created on 2018-12-28 by the reprex package (v0.2.1)}