Melange_ppx_lib.Ast_bs_openval convertBsErrorFunction :
Melange_compiler_libs.Location.t ->
Melange_compiler_libs.Ast_mapper.mapper ->
Melange_compiler_libs.Ast_helper.attrs ->
Melange_compiler_libs.Parsetree.case list ->
Melange_compiler_libs.Parsetree.expression