Fbe::Conclude#fill crashes with NoMethodError when follow property is missing on fact

[sdghsdkjlas27-dotcom]

conclude.rb line 249 calls prev[follow.to_s].each. In Factbase, if a property doesn't exist on a fact, fact[property] returns nil. Calling .each on nil raises NoMethodError. If a query matches facts where some lack the follow properties, the entire conclude operation crashes mid-transaction.

REPRODUCTION: Use follow('nonexistent_property') with a query that matches facts lacking that property.

IMPACT: RuntimeError/NoMethodError during conclude; partial processing (some facts processed, some not); factbase may be left in inconsistent state.

[VasilevNStas]

@yegor256

This was fixed as a side-effect of #596 — the next if values.nil? guard in Conclude#fill (lib/fbe/conclude.rb:280) now skips missing followed properties instead of crashing.

The issue can be closed.