From fe469a5455c59fc0dd9098fe45f78de75b02486a Mon Sep 17 00:00:00 2001
From: Johannes Schmidt <johannes.schmidt@icinga.com>
Date: Tue, 2 Jun 2026 10:19:02 +0200
Subject: [PATCH] Guard against assert() failures in SendJsonError()

Co-authored-by: Julian Brost <julian.brost@icinga.com>
---
 lib/remote/httputility.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/remote/httputility.cpp b/lib/remote/httputility.cpp
index 5e466bb8a..f868dae81 100644
--- a/lib/remote/httputility.cpp
+++ b/lib/remote/httputility.cpp
@@ -86,6 +86,16 @@ void HttpUtility::SendJsonBody(HttpApiResponse& response, const Dictionary::Ptr&
 void HttpUtility::SendJsonError(HttpApiResponse& response,
 	const Dictionary::Ptr& params, int code, const String& info, const String& diagnosticInformation)
 {
+	if (response.HasSerializationStarted()) {
+		std::ostringstream err;
+		err << "Impossible to send error response after streaming has started: error: '" << code << "', status: '"
+			<< info << "'";
+		if (!diagnosticInformation.IsEmpty()) {
+			err << ", diagnostic_information: '" << diagnosticInformation << "'";
+		}
+		BOOST_THROW_EXCEPTION(std::logic_error{err.str()});
+	}
+
 	Dictionary::Ptr result = new Dictionary({ { "error", code } });
 
 	if (!info.IsEmpty()) {