update run-tensorboard

check if env exists

run-tensorboard.bat

@@ -2,5 +2,12 @@
 setlocal
 title Tensorboard
 
+if not exist env (
+    echo Please run 'run-install.bat' first to set up the environment.
+    pause
+    exit /b 1
+)
+
 env\python.exe core.py tensorboard
-pause
+echo.
+pause