gh-1209: Node and 'undefined' in the process.env.foobar.

  Seems like Node checks for non-zero GetLastError()
  instead of ERROR_ENVVAR_NOT_FOUND after GetEnvironmentVariable call.

src/ConEmuHk/Entry.cpp

@@ -69,6 +69,7 @@ THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../common/HandleKeeper.h"
 #include "../common/PipeServer.h"
 #include "../common/ConEmuInOut.h"
+#include "../common/WErrGuard.h"
 
 #include "../ConEmuCD/ExitCodes.h"
 
@@ -441,6 +442,8 @@ CESERVER_CONSOLE_MAPPING_HDR* GetConMap(BOOL abForceRecreate/*=FALSE*/)
 	bool bAnsi = false;
 	bool bAnsiLog = false;
 
+	CLastErrorGuard errGuard;
+
 	if (gpConInfo && gpAppMap && !abForceRecreate)
 		goto wrap;
 

src/ConEmuHk/hkEnvironment.cpp

@@ -35,6 +35,7 @@ THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endif
 
 #include "../common/Common.h"
+#include "../common/WErrGuard.h"
 
 #include "Ansi.h"
 #include "hkEnvironment.h"
@@ -49,6 +50,7 @@ void CheckVariables()
 
 void CheckAnsiConVar(LPCWSTR asName)
 {
+	CLastErrorGuard errGuard;
 	bool bAnsi = false;
 	CEAnsi::GetFeatures(&bAnsi, NULL);