fn decl_error_set_fallible(decl_index: Decl.Index) Oom![]ErrorIdentifier
fn decl_error_set_fallible(decl_index: Decl.Index) Oom![]ErrorIdentifier { error_set_result.clearRetainingCapacity(); try addErrorsFromDecl(decl_index, &error_set_result); sort_error_set_result(); return error_set_result.values(); }