added a check for java and an error message

back/electron-tools.js

@@ -1,4 +1,4 @@
-const { BrowserWindow } = require("electron")
+const { BrowserWindow, dialog } = require("electron")
 
 
 function getMainWindow(){
@@ -12,6 +12,12 @@ function getMainWindow(){
 }
 
 
+function errorWindow(title, message){
+    dialog.showErrorBox(title, message)
+}
+
+
 module.exports = {
-    getMainWindow
+    getMainWindow,
+    errorWindow
 }

back/settings.js

@@ -2,14 +2,27 @@ const fs = require("fs")
 const path = require("path")
 const {appDataDir} = require("./config")
 const {findJava} = require("./utils");
+const {errorWindow} = require("./electron-tools");
+
+const javaPath = findJava()
+if(javaPath === null){
+    errorWindow(
+        "Java not found",
+        "No Java installation was found on your system.\n" +
+        "Please install at least one Java version and try again.\n\n" +
+        "If you have already installed Java, please make sure that it is in your PATH environment variable.\n\n" +
+        "Java can be downloaded from https://java.com/download"
+    )
+    process.exit(1)
+}
 
 class Settings {
     constructor(){
         this.settings = {
             credentials: null,
             ram: 1024,
             mcPath: path.join(appDataDir, "..", ".minecraft_swc"),
-            javaPath: findJava(),
+            javaPath: javaPath,
             "splash-width": "1280",
             "splash-height": "720",
             "launch-args": ""

back/utils.js

@@ -10,10 +10,14 @@ registerIpcListener("get-ram-amount", () => {
 
 
 function findJava() {
-    if(platform === "win32"){
-        return  child_process.execSync("where java.exe").toString().split("\r\n")[0]
-    }else{
-        return child_process.execSync("which java").toString().split("\n")[0]
+    try{
+        if(platform === "win32"){
+            return  child_process.execSync("where java.exe").toString().split("\r\n")[0]
+        }else{
+            return child_process.execSync("which java").toString().split("\n")[0]
+        }
+    } catch(e){
+        return null
     }
 }