Add venv creation message

build.bat

@@ -1,4 +1,6 @@
 @Echo off
+if not defined VIRTUAL_ENV goto :venv_error
+
 mkdir output
 mkdir output\bin
 python -m pip install -r FFMpeg-Compressor\requirements.txt || goto :exit
@@ -12,6 +14,10 @@ move /Y output\rendroid-unpack.exe output\bin
 python -m nuitka --jobs=%NUMBER_OF_PROCESSORS% --output-dir=output --follow-imports --onefile --output-filename=vnds2renpy VNDS-to-RenPy/convert.py || goto :exit
 move /Y output\vnds2renpy.exe output\bin
 
+:venv_error
+echo "Please create and activate venv before running this script: python -m venv .\venv && .\venv\Scripts\activate.bat"
+goto :exit
+
 :exit
 pause
 exit /b %exitlevel%

build.sh

@@ -1,5 +1,11 @@
-#!/bin/bash
+#!/usr/bin/env bash
 set -e
+if [[ "$VIRTUAL_ENV" == "" ]]
+then
+  echo -e "Please create and activate venv before running this script: \033[100mpython3 -m venv venv && source ./venv/bin/activate\033[49m"
+  exit
+fi
+
 mkdir -p output
 mkdir -p output/bin
 python3 -m pip install -r FFMpeg-Compressor/requirements.txt