When trying the function in my use case:

model <- mlogit(choice ~ attr_1+attr_2+attr_3, ewc_df2,
            child.var="DealerCode",
            alt.var='altkey',
            choice='choice',
            shape='long')

I am getting the following error:

Error in $<-: ! Assigned data value must be compatible with existing data. ✖ Existing data has 18329 rows. ✖ Assigned data has 18300 rows. ℹ Only vectors of size 1 are recycled. Caused by error in vectbl_recycle_rhs_rows(): ! Can't recycle input of size 18300 to size 18329.

Can't seem to find the reason why it's happening.