crash when choosing interactions and when deleting variables

[EIvimeyCook]

Produces these errors -

Warning in mean.default(z) :
argument is not numeric or logical: returning NA
Warning in stats::var(z) : NAs introduced by coercion
Warning in mean.default(z) :
argument is not numeric or logical: returning NA
Warning in stats::var(z) : NAs introduced by coercion
Warning: Error in [: subscript out of bounds