fix(frontends/lean): squiggle position for unary begin-end block
fix(frontends/lean): squiggle position for unary begin-end block

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