Better HTTP Error Handling (#199)

ldp/alg/rollout.py

@@ -10,6 +10,7 @@
 
 from ldp.agent import Agent
 from ldp.data_structures import Trajectory, Transition
+from ldp.utils import format_error_details
 
 from .callbacks import Callback
 
@@ -42,8 +43,9 @@ def reraise_exc_as(reraise: type[CaughtError], enabled: bool) -> Iterator[None]:
         yield
     except Exception as e:
         if enabled:
-            logger.exception(f"Caught {reraise.exc_type} exception.")
-            raise reraise(e) from e
+            error_details = format_error_details(e)
+            logger.exception(f"Caught {reraise.exc_type} exception:\n{error_details}")
+            raise reraise(e) from None
         raise
 
 

ldp/utils.py

@@ -2,6 +2,8 @@
 import logging.config
 from typing import Any
 
+logger = logging.getLogger(__name__)
+
 
 def configure_stdout_logs(
     name: str = "root",
@@ -80,3 +82,31 @@ def discounted_returns(
         returns.append(r)
     returns.reverse()
     return returns
+
+
+def format_error_details(error: Exception) -> str:
+    """Format detailed error information from an exception.
+
+    Specially handles HTTP errors that have response attributes with status codes
+    and JSON details, but works with any exception type.
+
+    Args:
+        error: The exception to format
+
+    Returns:
+        A formatted error string with available details
+    """
+    error_details = f"{error!s}"
+
+    if hasattr(error, "response"):
+        error_details += f"\nStatus code: {error.response.status_code}"
+        try:
+            response_data = error.response.json()
+            if "detail" in response_data:
+                error_details += "\nServer Traceback:\n"
+                for line in response_data["detail"].split("\n"):
+                    error_details += f"    {line}\n"
+        except Exception:
+            error_details += f"\nResponse body: {error.response.text}"
+
+    return error_details

tests/test_utils.py

@@ -0,0 +1,54 @@
+from dataclasses import dataclass
+from typing import Any
+
+from ldp.utils import format_error_details
+
+
+@dataclass
+class MockResponse:
+    status_code: int
+    _json: dict | None = None
+    _text: str = ""
+
+    def json(self) -> dict[str, Any]:
+        if self._json is None:
+            raise ValueError("No JSON")
+        return self._json
+
+    @property
+    def text(self) -> str:
+        return self._text
+
+
+class MockHTTPError(Exception):
+    def __init__(self, status_code: int, detail: str | None = None, text: str = ""):
+        self.response = MockResponse(
+            status_code=status_code,
+            _json={"detail": detail} if detail else None,
+            _text=text,
+        )
+        super().__init__(f"HTTP {status_code}")
+
+
+def test_format_basic_error():
+    error = ValueError("something went wrong")
+    details = format_error_details(error)
+    assert details == "something went wrong"
+
+
+def test_format_http_error_with_json():
+    error = MockHTTPError(
+        status_code=500,
+        detail="Traceback:\n  File 'app.py', line 123\n  raise ValueError('oops')",
+    )
+    details = format_error_details(error)
+    assert "Status code: 500" in details
+    assert "Server Traceback:" in details
+    assert "File 'app.py'" in details
+
+
+def test_format_http_error_with_text():
+    error = MockHTTPError(status_code=404, text="Not found")
+    details = format_error_details(error)
+    assert "Status code: 404" in details
+    assert "Response body: Not found" in details