Fix for #27

As NJannasch mentioned, the model won't work unless the model gets changed by llama.cpp\migrate-ggml-2023-03-30-pr613.py.

This batch works as follows

1) Activates the virtual environment and Runs the Python app.
2) If the model gives an error, it asks you [Y/N] if you want to fix the model, N exits the batch, Y fixes it.
3) It renames the model so it conserves the original, and then applies the fix as a new model. After that it tells that the model has been fixed. Press any key to restart.
4) Pressing a key makes the batch go to the start and the UI launches successfully.

run.bat

@@ -35,6 +35,33 @@ echo HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
 echo HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
 echo HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
 
-echo on
-call env/Scripts/activate.bat
-python app.py %*
+REM Activate the virtual environment
+call env\Scripts\activate.bat
+
+:RESTART
+REM Run the Python app
+python app.py %*
+set app_result=%errorlevel%
+
+IF %app_result% EQU 0 (
+    goto END
+) ELSE (
+    echo.
+    choice /C YN /M "The model file (gpt4all-lora-quantized-ggml.bin) appears to be invalid. Do you want to fix it?"
+    if errorlevel 2 goto END
+    if errorlevel 1 goto MODEL_FIX
+)
+
+:MODEL_FIX
+if not exist llama.cpp git clone https://github.com/ggerganov/llama.cpp.git
+move models\gpt4all-lora-quantized-ggml.bin models\gpt4all-lora-quantized-ggml.bin.original
+python llama.cpp\migrate-ggml-2023-03-30-pr613.py models\gpt4all-lora-quantized-ggml.bin.original models\gpt4all-lora-quantized-ggml.bin
+echo The model file (gpt4all-lora-quantized-ggml.bin) has been fixed. Press any key to restart...
+pause >nul
+goto RESTART
+
+:END
+REM Wait for user input before exiting
+echo.
+echo Press any key to exit...
+pause >nul