psbt: Only include m_tap_tree if it has scripts

Author: achow101

src/psbt.cpp

@@ -249,7 +249,7 @@ void PSBTOutput::FromSignatureData(const SignatureData& sigdata)
     if (!sigdata.tr_spenddata.internal_key.IsNull()) {
         m_tap_internal_key = sigdata.tr_spenddata.internal_key;
     }
-    if (sigdata.tr_builder.has_value()) {
+    if (sigdata.tr_builder.has_value() && sigdata.tr_builder->HasScripts()) {
         m_tap_tree = sigdata.tr_builder->GetTreeTuples();
     }
     for (const auto& [pubkey, leaf_origin] : sigdata.taproot_misc_pubkeys) {

src/script/standard.h

@@ -315,6 +315,8 @@ class TaprootBuilder
     TaprootSpendData GetSpendData() const;
     /** Returns a vector of tuples representing the depth, leaf version, and script */
     std::vector<std::tuple<uint8_t, uint8_t, CScript>> GetTreeTuples() const;
+    /** Returns true if there are any tapscripts */
+    bool HasScripts() const { return !m_branch.empty(); }
 };
 
 /** Given a TaprootSpendData and the output key, reconstruct its script tree.