fixed #46: because str_match() now returns character(0) when input is character(0), you should not use subset the result by [, 2]
fixed #46: because str_match() now returns character(0) when input is character(0), you should not use subset the result by [, 2]

fboehm/cboettig_site,antass/labnotebook3,fboehm/labnotebook,fboehm/cboettig_site,fboehm/labnotebook,fboehm/labnotebook,fboehm/cboettig_site,fboehm/labnotebook,antass/labnotebook3,antass/labnotebook3,fboehm/labnotebook,fboehm/cboettig_site,fboehm/labnotebook,fboehm/cboettig_site