fix(frontends/lean/server): '[anonymous]' entry being displayed by FINDP
fix(frontends/lean/server): '[anonymous]' entry being displayed by FINDP

This could happen when there is a declaration (e.g., nat) whose type is
equal to an active namespace.

soonhokong/lean,UlrikBuchholtz/lean,dselsam/lean,leodemoura/lean,fpvandoorn/lean2,dselsam/lean,soonhokong/lean-osx,levnach/lean,htzh/lean,dselsam/lean,fpvandoorn/lean,htzh/lean,c-cube/lean,leodemoura/lean,UlrikBuchholtz/lean,eigengrau/lean,UlrikBuchholtz/lean,rlewis1988/lean,digama0/lean,soonhokong/lean-windows,rlewis1988/lean,fpvandoorn/lean,fpvandoorn/lean,leodemoura/lean,fpvandoorn/lean2,soonhokong/lean-windows,htzh/lean,digama0/lean,rlewis1988/lean,fpvandoorn/lean2,fpvandoorn/lean2,soonhokong/lean-windows,fgdorais/lean,levnach/lean,soonhokong/lean-windows,levnach/lean,johoelzl/lean,sp3ctum/lean,fgdorais/lean,avigad/lean,fpvandoorn/lean2,digama0/lean,fgdorais/lean,c-cube/lean,eigengrau/lean,johoelzl/lean,johoelzl/lean,dselsam/lean,avigad/lean,leanprover-community/lean,rlewis1988/lean,leanprover/lean,soonhokong/lean-osx,javra/lean,avigad/lean,eigengrau/lean,htzh/lean,sp3ctum/lean,c-cube/lean,c-cube/lean,fgdorais/lean,soonhokong/lean,digama0/lean,leanprover/lean,avigad/lean,eigengrau/lean,Kha/lean,avigad/lean,sp3ctum/lean,soonhokong/lean,Kha/lean,leodemoura/lean,Kha/lean,soonhokong/lean-osx,fpvandoorn/lean,johoelzl/lean,rlewis1988/lean,dselsam/lean,digama0/lean,digama0/lean,c-cube/lean,soonhokong/lean-windows,leanprover-community/lean,fgdorais/lean,soonhokong/lean,leanprover/lean,avigad/lean,htzh/lean,johoelzl/lean,UlrikBuchholtz/lean,javra/lean,leanprover/lean,leodemoura/lean,leanprover-community/lean,leanprover-community/lean,levnach/lean,Kha/lean,Kha/lean,sp3ctum/lean,sp3ctum/lean,javra/lean,soonhokong/lean-osx,leanprover/lean,fpvandoorn/lean,levnach/lean,leanprover-community/lean,dselsam/lean,javra/lean,UlrikBuchholtz/lean,leodemoura/lean,johoelzl/lean,soonhokong/lean-osx,eigengrau/lean,soonhokong/lean,Kha/lean,javra/lean,leanprover/lean,leanprover-community/lean,rlewis1988/lean,fpvandoorn/lean,fgdorais/lean