fix(library/algebra/category/constructions): make proof more robust
fix(library/algebra/category/constructions): make proof more robust

soonhokong/lean,avigad/lean,soonhokong/lean,Kha/lean,soonhokong/lean-osx,soonhokong/lean-osx,soonhokong/lean-windows,digama0/lean,fpvandoorn/lean,johoelzl/lean,leanprover/lean,leanprover/lean,leodemoura/lean,johoelzl/lean,UlrikBuchholtz/lean,soonhokong/lean-osx,levnach/lean,leodemoura/lean,digama0/lean,UlrikBuchholtz/lean,digama0/lean,leanprover/lean,soonhokong/lean,dselsam/lean,avigad/lean,avigad/lean,digama0/lean,soonhokong/lean-windows,fgdorais/lean,levnach/lean,Kha/lean,soonhokong/lean,rlewis1988/lean,levnach/lean,leanprover-community/lean,leodemoura/lean,soonhokong/lean-windows,soonhokong/lean,soonhokong/lean-osx,Kha/lean,fgdorais/lean,avigad/lean,leanprover/lean,levnach/lean,javra/lean,UlrikBuchholtz/lean,fpvandoorn/lean,Kha/lean,dselsam/lean,fpvandoorn/lean2,johoelzl/lean,avigad/lean,digama0/lean,leanprover-community/lean,fgdorais/lean,fpvandoorn/lean2,leodemoura/lean,dselsam/lean,soonhokong/lean-windows,dselsam/lean,johoelzl/lean,fpvandoorn/lean2,leanprover/lean,rlewis1988/lean,fpvandoorn/lean,fgdorais/lean,UlrikBuchholtz/lean,rlewis1988/lean,rlewis1988/lean,avigad/lean,rlewis1988/lean,javra/lean,fpvandoorn/lean,fpvandoorn/lean2,UlrikBuchholtz/lean,soonhokong/lean-windows,rlewis1988/lean,fpvandoorn/lean,dselsam/lean,johoelzl/lean,Kha/lean,javra/lean,leanprover/lean,leodemoura/lean,fpvandoorn/lean2,leanprover-community/lean,leanprover-community/lean,fgdorais/lean,javra/lean,javra/lean,dselsam/lean,leanprover-community/lean,Kha/lean,fpvandoorn/lean,soonhokong/lean-osx,johoelzl/lean,leodemoura/lean,levnach/lean,fgdorais/lean,leanprover-community/lean,digama0/lean