Adding safe check when source equals to -1 (#3054)
Adding safe check when source equals to -1 (#3054)

FEC-6091
kaltura/mwEmbed,FlixMaster/mwEmbed,FlixMaster/mwEmbed,omridevk/mwEmbed,panda-os/mwEmbed,tanyaLibatter/mwEmbed,tanyaLibatter/mwEmbed,kaltura/mwEmbed,panda-os/mwEmbed,panda-os/mwEmbed,slash851/mwEmbed,alexmilk/mwEmbed,bordar/mwEmbed,omridevk/mwEmbed,bordar/mwEmbed,alexmilk/mwEmbed,kaltura/mwEmbed,bordar/mwEmbed,panda-os/mwEmbed,FlixMaster/mwEmbed,alexmilk/mwEmbed,tanyaLibatter/mwEmbed,slash851/mwEmbed,bordar/mwEmbed,slash851/mwEmbed,alexmilk/mwEmbed,FlixMaster/mwEmbed,kaltura/mwEmbed,omridevk/mwEmbed,omridevk/mwEmbed,slash851/mwEmbed,tanyaLibatter/mwEmbed