From c6dbb792eb7244418937a33b48941f25d41aa8bf Mon Sep 17 00:00:00 2001
From: evoskuil <eric@voskuil.org>
Date: Sun, 2 Jun 2024 14:13:18 -0400
Subject: [PATCH 1/2] Add error::txs_empty.

---
 include/bitcoin/database/error.hpp | 1 +
 src/error.cpp                      | 1 +
 test/error.cpp                     | 9 +++++++++
 3 files changed, 11 insertions(+)

diff --git a/include/bitcoin/database/error.hpp b/include/bitcoin/database/error.hpp
index 96156cd4..5a659c7b 100644
--- a/include/bitcoin/database/error.hpp
+++ b/include/bitcoin/database/error.hpp
@@ -118,6 +118,7 @@ enum error_t : uint8_t
     tx_tx_commit,
 
     /// txs archive
+    txs_empty,
     txs_header,
     txs_txs_put,
     txs_confirm
diff --git a/src/error.cpp b/src/error.cpp
index 74d5026d..a27f0905 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -110,6 +110,7 @@ DEFINE_ERROR_T_MESSAGE_MAP(error)
     { tx_tx_commit, "tx_tx_commit" },
 
     // tx archive
+    { txs_empty, "txs_empty" },
     { txs_header, "txs_header" },
     { txs_txs_put, "txs_txs_put" },
     { txs_confirm, "txs_confirm" }
diff --git a/test/error.cpp b/test/error.cpp
index df6b06f0..e2167fd7 100644
--- a/test/error.cpp
+++ b/test/error.cpp
@@ -603,6 +603,15 @@ BOOST_AUTO_TEST_CASE(error_t__code__txs_header__true_exected_message)
     BOOST_REQUIRE_EQUAL(ec.message(), "txs_header");
 }
 
+BOOST_AUTO_TEST_CASE(error_t__code__txs_empty__true_exected_message)
+{
+    constexpr auto value = error::txs_empty;
+    const auto ec = code(value);
+    BOOST_REQUIRE(ec);
+    BOOST_REQUIRE(ec == value);
+    BOOST_REQUIRE_EQUAL(ec.message(), "txs_empty");
+}
+
 BOOST_AUTO_TEST_CASE(error_t__code__txs_txs_put__true_exected_message)
 {
     constexpr auto value = error::txs_txs_put;

From e32eb7cf30141fe486ee77f8c68142bf70f9251c Mon Sep 17 00:00:00 2001
From: evoskuil <eric@voskuil.org>
Date: Sun, 2 Jun 2024 14:13:42 -0400
Subject: [PATCH 2/2] Check for txs.empty() upon association.

---
 include/bitcoin/database/impl/query/archive.ipp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/bitcoin/database/impl/query/archive.ipp b/include/bitcoin/database/impl/query/archive.ipp
index ced0f21d..a7535575 100644
--- a/include/bitcoin/database/impl/query/archive.ipp
+++ b/include/bitcoin/database/impl/query/archive.ipp
@@ -965,6 +965,9 @@ code CLASS::set_code(txs_link& out_fk, const transactions& txs,
     if (key.is_terminal())
         return error::txs_header;
 
+    if (txs.empty())
+        return error::txs_empty;
+
     ////// GUARD (block (txs) redundancy)
     ////// This is only fully effective if there is a single database thread.
     ////// Guard must be lifted for an existing top malleable association so