Change CoreWalletService#getAvailableBalance from Tuple2 to long

And throw an IllegalStateException with an appropriate message if the
wallet is not available or still locked.

This change also eliminates the NullPointerException that would
sometimes be thrown when calling #getAvailableBalance after the wallet
has become available but before the balance has become available.

core/src/main/java/bisq/core/grpc/ApiStatus.java

@@ -42,8 +42,6 @@ enum ApiStatus {
     WALLET_ENCRYPTER_NOT_AVAILABLE(Status.FAILED_PRECONDITION, "wallet encrypter is not available"),
 
     WALLET_IS_ENCRYPTED(Status.FAILED_PRECONDITION, "wallet is encrypted with a password"),
-    WALLET_IS_ENCRYPTED_WITH_UNLOCK_INSTRUCTION(Status.FAILED_PRECONDITION,
-            "wallet is encrypted with a password; unlock it with the 'unlock \"password\" timeout' command"),
 
     WALLET_NOT_ENCRYPTED(Status.FAILED_PRECONDITION, "wallet is not encrypted with a password"),
     WALLET_NOT_AVAILABLE(Status.UNAVAILABLE, "wallet is not available");

core/src/main/java/bisq/core/grpc/CoreWalletService.java

@@ -36,22 +36,18 @@ public CoreWalletService(Balances balances, WalletsManager walletsManager) {
         this.walletsManager = walletsManager;
     }
 
-    public Tuple2<Long, ApiStatus> getAvailableBalance() {
+    public long getAvailableBalance() {
         if (!walletsManager.areWalletsAvailable())
-            return new Tuple2<>(-1L, WALLET_NOT_AVAILABLE);
+            throw new IllegalStateException("wallet is not yet available");
 
         if (walletsManager.areWalletsEncrypted())
-            return new Tuple2<>(-1L, WALLET_IS_ENCRYPTED_WITH_UNLOCK_INSTRUCTION);
+            throw new IllegalStateException("wallet is locked");
 
-        try {
-            long balance = balances.getAvailableBalance().get().getValue();
-            return new Tuple2<>(balance, OK);
-        } catch (Throwable t) {
-            // TODO Derive new ApiStatus codes from server stack traces.
-            t.printStackTrace();
-            // TODO Fix bug causing NPE thrown by getAvailableBalance().
-            return new Tuple2<>(-1L, INTERNAL);
-        }
+        var balance = balances.getAvailableBalance().get();
+        if (balance == null)
+            throw new IllegalStateException("balance is not yet available");
+
+        return balance.getValue();
     }
 
     public Tuple2<Boolean, ApiStatus> setWalletPassword(String password, String newPassword) {

core/src/main/java/bisq/core/grpc/GrpcWalletService.java

@@ -12,6 +12,7 @@
 import bisq.proto.grpc.UnlockWalletRequest;
 import bisq.proto.grpc.WalletGrpc;
 
+import io.grpc.Status;
 import io.grpc.StatusRuntimeException;
 import io.grpc.stub.StreamObserver;
 
@@ -28,16 +29,16 @@ public GrpcWalletService(CoreWalletService walletService) {
 
     @Override
     public void getBalance(GetBalanceRequest req, StreamObserver<GetBalanceReply> responseObserver) {
-        var result = walletService.getAvailableBalance();
-        if (!result.second.equals(ApiStatus.OK)) {
-            StatusRuntimeException ex = new StatusRuntimeException(result.second.getGrpcStatus()
-                    .withDescription(result.second.getDescription()));
+        try {
+            long result = walletService.getAvailableBalance();
+            var reply = GetBalanceReply.newBuilder().setBalance(result).build();
+            responseObserver.onNext(reply);
+            responseObserver.onCompleted();
+        } catch (IllegalStateException cause) {
+            var ex = new StatusRuntimeException(Status.UNAVAILABLE.withDescription(cause.getMessage()));
             responseObserver.onError(ex);
             throw ex;
         }
-        var reply = GetBalanceReply.newBuilder().setBalance(result.first).build();
-        responseObserver.onNext(reply);
-        responseObserver.onCompleted();
     }
 
     @Override