From 0cc9ddba0588953409a4398cdc22b1d7139a0c4f Mon Sep 17 00:00:00 2001
From: Craig Raw <craigraw@gmail.com>
Date: Tue, 14 Feb 2023 09:57:23 +0200
Subject: [PATCH] read and throw hwi error stream if stdout empty

---
 .../com/sparrowwallet/sparrow/io/Hwi.java     | 26 ++++++++++++++-----
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/src/main/java/com/sparrowwallet/sparrow/io/Hwi.java b/src/main/java/com/sparrowwallet/sparrow/io/Hwi.java
index 7f073c21..a9f7ff53 100644
--- a/src/main/java/com/sparrowwallet/sparrow/io/Hwi.java
+++ b/src/main/java/com/sparrowwallet/sparrow/io/Hwi.java
@@ -290,9 +290,7 @@ public class Hwi {
         try {
             ProcessBuilder processBuilder = new ProcessBuilder(command);
             process = processBuilder.start();
-            try(InputStreamReader reader = new InputStreamReader(process.getInputStream(), StandardCharsets.UTF_8)) {
-                return CharStreams.toString(reader);
-            }
+            return getProcessOutput(process);
         } finally {
             deleteExtractionOnFailure(process, start);
         }
@@ -318,14 +316,30 @@ public class Hwi {
                 writer.flush();
             }
 
-            try(InputStreamReader reader = new InputStreamReader(process.getInputStream(), StandardCharsets.UTF_8)) {
-                return CharStreams.toString(reader);
-            }
+            return getProcessOutput(process);
         } finally {
             deleteExtractionOnFailure(process, start);
         }
     }
 
+    private String getProcessOutput(Process process) throws IOException {
+        String output;
+        try(InputStreamReader reader = new InputStreamReader(process.getInputStream(), StandardCharsets.UTF_8)) {
+            output = CharStreams.toString(reader);
+        }
+
+        if(output.isEmpty() && process.getErrorStream() != null) {
+            try(InputStreamReader reader = new InputStreamReader(process.getErrorStream(), StandardCharsets.UTF_8)) {
+                String errorOutput = CharStreams.toString(reader);
+                if(!errorOutput.isEmpty()) {
+                    throw new IOException(errorOutput);
+                }
+            }
+        }
+
+        return output;
+    }
+
     private synchronized File getHwiExecutable(Command command) {
         File hwiExecutable = Config.get().getHwi();
         if(hwiExecutable != null && hwiExecutable.exists()) {