From ed3e61cabb23f9495801b75b9041c3e2dc4891e5 Mon Sep 17 00:00:00 2001
From: "Lars T. Kyllingstad" <lars.kyllingstad@sintef.no>
Date: Tue, 21 Oct 2025 10:51:59 +0200
Subject: [PATCH] Don't crash if FMUs log with category=NULL

This fixes issue #796.
---
 src/cosim/fmi/v1/fmu.cpp | 3 ++-
 src/cosim/fmi/v2/fmu.cpp | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/cosim/fmi/v1/fmu.cpp b/src/cosim/fmi/v1/fmu.cpp
index cf011dac..c48335bb 100644
--- a/src/cosim/fmi/v1/fmu.cpp
+++ b/src/cosim/fmi/v1/fmu.cpp
@@ -236,7 +236,8 @@ void log_message(
             break;
     }
     BOOST_LOG_SEV(log::logger(), logLevel)
-        << "[FMI status=" << statusName << ", category=" << category << "] "
+        << "[FMI status=" << statusName
+        << ", category=" << (category ? category : "") << "] "
         << msgBuffer.data();
 
     g_logMutex.lock();
diff --git a/src/cosim/fmi/v2/fmu.cpp b/src/cosim/fmi/v2/fmu.cpp
index 47234e91..fdeee53b 100644
--- a/src/cosim/fmi/v2/fmu.cpp
+++ b/src/cosim/fmi/v2/fmu.cpp
@@ -243,7 +243,8 @@ void log_message(
             break;
     }
     BOOST_LOG_SEV(log::logger(), logLevel)
-        << "[FMI status=" << statusName << ", category=" << category << "] "
+        << "[FMI status=" << statusName
+        << ", category=" << (category ? category : "") << "] "
         << msgBuffer.data();
 
     g_logMutex.lock();