Steps to reproduce:

* Build with `integer` sanitizer
* Start: `UBSAN_OPTIONS="suppressions=$(pwd)/test/sanitizer_suppressions/ubsan:print_stacktrace=1:halt_on_error=1:report_error_type=1" ./src/qt/bitcoin-qt -chain=main`
* Enter `getdescriptorinfo "sh(multi(1,xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/5/5/5/2/8/5/8/8/8/2/2/5/8/5/2/5/85/58/5/2/5/5/5/5/2/58/2/5/8/0000/00/8/5/2/001/1/246/8/501/46/8/5/8/5/000/8/52/5/8/5/2/8/2/5/8/5/246/8/5/2/8/2/5/8/5/2/5/8/8/2/5/5/5/58/88/2/6/8/5/2/8/2/5/8/2/588/5/2/5/8/5/2/8/5/1/5/4/5/5/5/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/8/58/588/2/52/5/5/5/58/8/2/6/8/5/2/8/2/5/8/2/588/5/2/5/8/5/2/8/5/15/58/58/2/6/8/5/2/8/2/5/8/5/2/5/8/58/2/5/58/58/588/2/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/2/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/8/588/2/6/8/5/2/8/2/5/5/8/5/2/0/8/5/2/00/4/5/5/588/2/6/8/5/2/8/25/5/8/2/5/58/58/8/4/1,[00000000]xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L/58)0)"` into the console
auto sarg = Expr(expr);
                subscripts.emplace_back(ParseScript(key_exp_index, sarg, ParseScriptContext::P2TR, out, error));
                if (!subscripts.back()) return nullptr;
                depths.push_back(branches.size());
                
                while (branches.size() && branches.back()) {
                    if (!Const("}", expr)) {
                        error = strprintf("tr(): expected '}' after script expression");
                        return nullptr;
                    }
                    branches.pop_back(); 
                }
                
                if (branches.size() && !branches.back()) {
                    if (!Const(",", expr)) {
                        error = strprintf("tr(): expected ',' after script expression");
                        return nullptr;
                    }
                    branches.back() = true; 
                }
            } while (branches.size());
            
            if (expr.size()) {
                error = strprintf("tr(): expected ')' after script expression");
                return nullptr;
            }
        }
        assert(TaprootBuilder::ValidDepths(depths));
        return std::make_unique<TRDescriptor>(std::move(internal_key), std::move(subscripts), std::move(depths));