lets see if this fixes the issue

src/fsfw_hal/linux/UnixFileGuard.h

@@ -15,7 +15,15 @@ class UnixFileGuard {
 
   static constexpr ReturnValue_t OPEN_FILE_FAILED = 1;
 
-  UnixFileGuard(const std::string& device, int* fileDescriptor, int flags,
+  /**
+   * Open a device and assign the given file descriptor variable
+   * @param device [in] Device name.
+   * @param fileDescriptor [in/out] Will be assigned by file guard and re-used to
+   *    close the guard.
+   * @param flags
+   * @param diagnosticPrefix
+   */
+  UnixFileGuard(const std::string& device, int& fileDescriptor, int flags,
                 std::string diagnosticPrefix = "");
 
   virtual ~UnixFileGuard();
@@ -23,7 +31,7 @@ class UnixFileGuard {
   ReturnValue_t getOpenResult() const;
 
  private:
-  int* fileDescriptor = nullptr;
+  int fileDescriptor = 0;
   ReturnValue_t openStatus = returnvalue::OK;
 };