Incorrect parsing of multiple event types

[jburos]

Example:

> subjects <- fetch_subjects(event_type = c('new_lesion', 'nontarget_progression'))
Error: Geco API request failed [400: Event type new_lesion,nontarget_progression is not of of ['true_overall_survival', 'progression', 'newlesion_progression', 'nontarget_progression', 'progression_free_survival', 'overall_survival', 'new_lesion', 'target_progression']]
> subjects <- fetch_subjects(event_type = list('new_lesion', 'nontarget_progression'))
Error: Geco API request failed [400: Event type new_lesion,nontarget_progression is not of of ['true_overall_survival', 'progression', 'newlesion_progression', 'nontarget_progression', 'progression_free_survival', 'overall_survival', 'new_lesion', 'target_progression']]