cubicweb #3119950 crash in EtypeRestrictionComponent [validation pending]

when multiple etypes due to is_instance_of are involved, eg "Any X ORDERBY R WHERE X ref LIKE "LGLB%", X is_instance_of Workcase, X ref R" on our internal crm

prioritynormal
typebug
done in3.19.0
load0.100
load left0.000
closed by<not specified>
patch[ui component] fix potential crash in ETypeRestrictionComponent. Closes #3119950 [rejected]