Function validate_table 

pub fn validate_table(routing: &RoutingConfig) -> Result<(), String>

Fail-closed validation of the routing table, called by crate::config::validate so a malformed table never reaches a mission. Returns Err naming the offending rule (the config-file key path), never a silently-corrected table:

• a blank taskClass could never match honestly (routing matches on task-class text), and
• a duplicate class after normalization is dead config under first-match-wins — almost always a mistake the operator meant to reorder or merge, so it is refused rather than quietly shadowed.

The same two checks apply to patternRules (ticket routing-rules-config): a blank pattern is meaningless (spell *), and a duplicate pattern is dead config under first-match-wins.