fix(frontends/lean/tactic_notation): remove problematic code for get_begin_end_block_elements
fix(frontends/lean/tactic_notation): remove problematic code for get_begin_end_block_elements

rlewis1988/lean,fpvandoorn/lean,avigad/lean,leanprover/lean,johoelzl/lean,leanprover-community/lean,digama0/lean,fgdorais/lean,leodemoura/lean,leodemoura/lean,leanprover/lean,digama0/lean,fpvandoorn/lean,digama0/lean,rlewis1988/lean,leanprover/lean,dselsam/lean,fgdorais/lean,leodemoura/lean,Kha/lean,rlewis1988/lean,leanprover-community/lean,Kha/lean,leanprover/lean,dselsam/lean,leanprover/lean,fgdorais/lean,Kha/lean,johoelzl/lean,digama0/lean,leodemoura/lean,avigad/lean,Kha/lean,fgdorais/lean,fpvandoorn/lean,johoelzl/lean,fpvandoorn/lean,dselsam/lean,dselsam/lean,dselsam/lean,rlewis1988/lean,leanprover-community/lean,johoelzl/lean,digama0/lean,rlewis1988/lean,fgdorais/lean,rlewis1988/lean,leanprover/lean,fgdorais/lean,dselsam/lean,Kha/lean,johoelzl/lean,johoelzl/lean,Kha/lean,digama0/lean,avigad/lean,leanprover-community/lean,avigad/lean,leodemoura/lean,leanprover-community/lean,fpvandoorn/lean,avigad/lean,leodemoura/lean,leanprover-community/lean,fpvandoorn/lean,avigad/lean