edeaR filter_infrequent_flows is not robust against event logs with `label` column and integer `activity_instance` column

[fmannhardt]

I don't have the time to make a repex but want to post this so I don't forget.
Debugged down the issue with the function to be a column named label.

I think it goes wrong here (which is actually in base bupaR):

add_start_activity <- function(log, label = "Start") {    
    log %>%
      group_by_case() %>%
      arrange(.data[[timestamp(log)]]) %>%
      slice_events(1) %>%
      ungroup_eventlog() %>%
      mutate(!!timestamp(log) := .data[[timestamp(log)]] - 1,
             !!activity_id(log) := factor(label, levels = c(as.character(bupaR::activity_labels(log)), label)),
             !!activity_instance_id(log) := stri_c(.data[[case_id(log)]], "start", sep = "-")) -> start_states
    
    return(add_start_end_activity_bind_logs(log, start_states, label))
  }  

It seems dplyr somehow evaluates some of the label variables to the column and not the parameter.
The other issue is the stri_c command to define the activity instance clashes if the instance is an int column.

Probably this should be moved to bupaR but this is how I got to the error.