Log request body on 422 responses

jbi/app.py

@@ -128,11 +128,19 @@ async def validation_exception_handler(
     errors in order to log some information about malformed
     requests.
     """
+    try:
+        request_body = (await request.body()).decode("utf8")
+    except UnicodeDecodeError:  # pragma: no cover
+        # In theory FastAPI would have returned a 400 before doing
+        # model validation.
+        request_body = "<invalid unicode>"
+
     logger.error(
         "invalid incoming request: %s",
         exc,
         extra={
             "errors": exc.errors(),
+            "body": request_body,
         },
     )
     return JSONResponse(

tests/unit/test_app.py

@@ -51,6 +51,7 @@ def test_422_errors_are_logged(authenticated_client, webhook_request_factory, ca
         logged.errors[0]["msg"]
         == "Input should be a valid dictionary or object to extract fields from"
     )
+    assert '"bug":null' in logged.body
 
 
 @pytest.mark.parametrize(