fix: [stix2 export] Fixed enumeration errors handling
fix: [stix2 export] Fixed enumeration errors handling

- More specific exception types
- Removed useless try/catch statement

SteveClement/MISP,MISP/MISP,FIRSTdotorg/MISP,SteveClement/MISP,Rafiot/MISP,SteveClement/MISP,FIRSTdotorg/MISP,FIRSTdotorg/MISP,FloatingGhost/MISP,devnull-/MISP,SteveClement/MISP,Rafiot/MISP,FloatingGhost/MISP,devnull-/MISP,Rafiot/MISP,MISP/MISP,MISP/MISP,FIRSTdotorg/MISP,SteveClement/MISP,MISP/MISP,devnull-/MISP,devnull-/MISP,Rafiot/MISP,FloatingGhost/MISP,FloatingGhost/MISP,MISP/MISP