fix: proof result error for credit transfers in sdk (#2451)

Author: pauldelucia

packages/rs-sdk/src/platform/transition/transfer.rs

@@ -32,7 +32,7 @@ pub trait TransferToIdentity: Waitable {
         signing_transfer_key_to_use: Option<&IdentityPublicKey>,
         signer: S,
         settings: Option<PutSettings>,
-    ) -> Result<u64, Error>;
+    ) -> Result<(u64, u64), Error>;
 }
 
 #[async_trait::async_trait]
@@ -45,7 +45,7 @@ impl TransferToIdentity for Identity {
         signing_transfer_key_to_use: Option<&IdentityPublicKey>,
         signer: S,
         settings: Option<PutSettings>,
-    ) -> Result<u64, Error> {
+    ) -> Result<(u64, u64), Error> {
         let new_identity_nonce = sdk.get_identity_nonce(self.id(), true, settings).await?;
         let user_fee_increase = settings.and_then(|settings| settings.user_fee_increase);
         let state_transition = IdentityCreditTransferTransition::try_from_identity(
@@ -60,10 +60,21 @@ impl TransferToIdentity for Identity {
             None,
         )?;
 
-        let identity: PartialIdentity = state_transition.broadcast_and_wait(sdk, settings).await?;
+        let (sender, receiver): (PartialIdentity, PartialIdentity) =
+            state_transition.broadcast_and_wait(sdk, settings).await?;
 
-        identity.balance.ok_or(Error::DapiClientError(
-            "expected an identity balance after transfer".to_string(),
-        ))
+        let sender_balance = sender.balance.ok_or_else(|| {
+            Error::DapiClientError(
+                "expected an identity balance after transfer (sender)".to_string(),
+            )
+        })?;
+
+        let receiver_balance = receiver.balance.ok_or_else(|| {
+            Error::DapiClientError(
+                "expected an identity balance after transfer (receiver)".to_string(),
+            )
+        })?;
+
+        Ok((sender_balance, receiver_balance))
     }
 }