Fix: add header guard

Author: ariedel-cern

GPU/GPUTracking/Global/GPUErrors.h

@@ -16,7 +16,6 @@
 #define GPUERRORS_H
 
 #include "GPUCommonDef.h"
-
 #ifndef GPUCA_GPUCODE
 #include <unordered_map>
 #endif
@@ -38,7 +37,9 @@ class GPUErrors
   void setMemory(GPUglobalref() uint32_t* m) { mErrors = m; }
   void clear();
   bool printErrors(bool silent = false, uint64_t mask = 0);
+#ifndef GPUCA_GPUCODE
   static const std::unordered_map<uint32_t, const char*>& getErrorNames();
+#endif
   uint32_t getNErrors() const;
   const uint32_t* getErrorPtr() const;
   static uint32_t getMaxErrors();