Fix handleApiReturn

src/service.ts

@@ -981,6 +981,23 @@ export class Service {
   }
 
   public async handleApiReturn(apiReturn: ApiReturn) {
+    // Check for errors in the returned objects
+    if (apiReturn.new_tx_to_send && apiReturn.new_tx_to_send.error) {
+      const error = apiReturn.new_tx_to_send.error;
+      const errorMessage = typeof error === 'object' && error !== null ? 
+        (error as any).GenericError || JSON.stringify(error) : 
+        String(error);
+      throw new Error(`Transaction error: ${errorMessage}`);
+    }
+
+    if (apiReturn.commit_to_send && apiReturn.commit_to_send.error) {
+      const error = apiReturn.commit_to_send.error;
+      const errorMessage = typeof error === 'object' && error !== null ? 
+        (error as any).GenericError || JSON.stringify(error) : 
+        String(error);
+      throw new Error(`Commit error: ${errorMessage}`);
+    }
+
     if (apiReturn.partial_tx) {
       try {
         const res = wasm.sign_transaction(apiReturn.partial_tx);