Check Node.js version, better error message

server/server.js

@@ -1,4 +1,15 @@
 console.log("Welcome to Uptime Kuma");
+
+// Check Node.js Version
+const nodeVersion = parseInt(process.versions.node.split(".")[0]);
+const requiredVersion = 14;
+console.log(`Your Node.js version: ${nodeVersion}`);
+
+if (nodeVersion < requiredVersion) {
+    console.error(`Error: Your Node.js version is not supported, please upgrade to Node.js >= ${requiredVersion}.`);
+    process.exit(-1);
+}
+
 const args = require("args-parser")(process.argv);
 const { sleep, debug, getRandomInt, genSecret } = require("../src/util");
 const config = require("./config");