Fix fetching asset-related transactions from DB where asset might not exist.

Some asset-related transactions (CREATE_ASSET_ORDER and TRANSFER_ASSET)
also try to fetch asset names at the same time.

If one of these transactions, and a corresponding ISSUE_ASSET transaction,
have been orphaned then it's possible that the asset no longer exists.

Thus the SQL "JOIN" fails during transaction retrieval, causing an error.

Changing the table-join to "LEFT OUTER JOIN" makes the asset name aspect
optional. Repercussions might be nameless assets when fetching transaction
info via API.

src/main/java/org/qora/repository/hsqldb/transaction/HSQLDBCreateAssetOrderTransactionRepository.java

@@ -18,10 +18,11 @@ public class HSQLDBCreateAssetOrderTransactionRepository extends HSQLDBTransacti
 	}
 
 	TransactionData fromBase(BaseTransactionData baseTransactionData) throws DataException {
+		// LEFT OUTER JOIN because asset might not exist (e.g. if ISSUE_ASSET & CREATE_ASSET_ORDER are both unconfirmed)
 		String sql = "SELECT have_asset_id, amount, want_asset_id, price, HaveAsset.asset_name, WantAsset.asset_name "
 				+ "FROM CreateAssetOrderTransactions "
-				+ "JOIN Assets AS HaveAsset ON HaveAsset.asset_id = have_asset_id "
-				+ "JOIN Assets AS WantAsset ON WantAsset.asset_id = want_asset_id "
+				+ "LEFT OUTER JOIN Assets AS HaveAsset ON HaveAsset.asset_id = have_asset_id "
+				+ "LEFT OUTER JOIN Assets AS WantAsset ON WantAsset.asset_id = want_asset_id "
 				+ "WHERE signature = ?";
 
 		try (ResultSet resultSet = this.repository.checkedExecute(sql, baseTransactionData.getSignature())) {

src/main/java/org/qora/repository/hsqldb/transaction/HSQLDBTransactionRepository.java

@@ -28,6 +28,7 @@ import org.qora.repository.hsqldb.HSQLDBRepository;
 import org.qora.repository.hsqldb.HSQLDBSaver;
 import org.qora.transaction.Transaction.ApprovalStatus;
 import org.qora.transaction.Transaction.TransactionType;
+import org.qora.utils.Base58;
 
 import static org.qora.transaction.Transaction.TransactionType.*;
 
@@ -938,7 +939,7 @@ public class HSQLDBTransactionRepository implements TransactionRepository {
 
 				if (transactionData == null)
 					// Something inconsistent with the repository
-					throw new DataException("Unable to fetch unconfirmed transaction from repository?");
+					throw new DataException(String.format("Unable to fetch unconfirmed transaction %s from repository?", Base58.encode(signature)));
 
 				transactions.add(transactionData);
 			} while (resultSet.next());

src/main/java/org/qora/repository/hsqldb/transaction/HSQLDBTransferAssetTransactionRepository.java

@@ -18,7 +18,8 @@ public class HSQLDBTransferAssetTransactionRepository extends HSQLDBTransactionR
 	}
 
 	TransactionData fromBase(BaseTransactionData baseTransactionData) throws DataException {
-		String sql = "SELECT recipient, asset_id, amount, asset_name FROM TransferAssetTransactions JOIN Assets USING (asset_id) WHERE signature = ?";
+		// LEFT OUTER JOIN because asset might not exist (e.g. if ISSUE_ASSET & TRANSFER_ASSET are both unconfirmed)
+		String sql = "SELECT recipient, asset_id, amount, asset_name FROM TransferAssetTransactions LEFT OUTER JOIN Assets USING (asset_id) WHERE signature = ?";
 
 		try (ResultSet resultSet = this.repository.checkedExecute(sql, baseTransactionData.getSignature())) {
 			if (resultSet == null)