wallet2.get_reserve_proof: throw when specified amount is zero

src/wallet/wallet2.cpp

@@ -8915,6 +8915,7 @@ std::string wallet2::get_reserve_proof(const boost::optional<std::pair<uint32_t,
 
   if (account_minreserve)
   {
+    THROW_WALLET_EXCEPTION_IF(account_minreserve->second == 0, error::wallet_internal_error, "Proved amount must be greater than 0");
     // minimize the number of outputs included in the proof, by only picking the N largest outputs that can cover the requested min reserve amount
     std::sort(selected_transfers.begin(), selected_transfers.end(), [&](const size_t a, const size_t b)
       { return m_transfers[a].amount() > m_transfers[b].amount(); });