improve handling of certain electrum server errors

src/main/java/com/sparrowwallet/sparrow/net/SimpleElectrumServerRpc.java

@@ -150,7 +150,7 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
                 //If there is an error with the server connection, don't keep trying - this may take too long given many blocks
                 throw new ElectrumServerRpcException("Failed to retrieve block header for block height: " + blockHeight, e);
             } catch(JsonRpcException e) {
-                log.warn("Failed to retrieve block header for block height: " + blockHeight + " (" + e.getErrorMessage() + ")");
+                log.warn("Failed to retrieve block header for block height: " + blockHeight + (e.getErrorMessage() != null ? " (" + e.getErrorMessage().getMessage() + ")" : ""));
             } catch(Exception e) {
                 log.warn("Failed to retrieve block header for block height: " + blockHeight + " (" + e.getMessage() + ")");
             }
@@ -193,6 +193,11 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
                         client.createRequest().returnAs(VerboseTransaction.class).method("blockchain.transaction.get").id(idCounter.incrementAndGet()).params(txid, true).execute());
                 result.put(txid, verboseTransaction);
             } catch(Exception e) {
+                if(e instanceof JsonRpcException jsonRpcException && jsonRpcException.getErrorMessage() != null
+                        && jsonRpcException.getErrorMessage().getMessage().startsWith("No such mempool or blockchain transaction")) {
+                    continue;
+                }
+
                 //electrs-esplora does not currently support the verbose parameter, so try to fetch an incomplete VerboseTransaction without it
                 //Note that without the script hash associated with the transaction, we can't get a block height as there is no way in the Electrum RPC protocol to do this
                 //We mark this VerboseTransaction as incomplete by assigning it a Sha256Hash.ZERO_HASH blockhash

src/main/java/com/sparrowwallet/sparrow/transaction/HeadersController.java

@@ -1109,11 +1109,18 @@ public class HeadersController extends TransactionFormController implements Init
         broadcastTransactionService.setOnFailed(workerStateEvent -> {
             broadcastProgressBar.setProgress(0);
             log.error("Error broadcasting transaction", workerStateEvent.getSource().getException());
-            if(workerStateEvent.getSource().getException() != null && workerStateEvent.getSource().getException().getMessage() != null
+
-                    && workerStateEvent.getSource().getException().getMessage().startsWith("min relay fee not met")) {
+            String failMessage = "";
+            if(workerStateEvent.getSource().getException() != null && workerStateEvent.getSource().getException().getMessage() != null) {
+                failMessage = workerStateEvent.getSource().getException().getMessage();
+            }
+
+            if(failMessage.startsWith("min relay fee not met")) {
                 AppServices.showErrorDialog("Error broadcasting transaction", "The fee rate for the signed transaction is below the minimum " + AppServices.getMinimumRelayFeeRate() + " sats/vB. " +
                         "This usually happens because a keystore has created a signature that is larger than necessary.\n\n" +
                         "You can solve this by recreating the transaction with a slightly increased fee rate.");
+            } else if(failMessage.startsWith("bad-txns-inputs-missingorspent")) {
+                AppServices.showErrorDialog("Error broadcasting transaction", "The server returned an error indicating some or all of the UTXOs this transaction is spending are missing or have already been spent.");
             } else {
                 AppServices.showErrorDialog("Error broadcasting transaction", "The server returned an error when broadcasting the transaction. The server response is contained in the log (See Help > Show Log File).");
             }