fix: RAILWAY_PUBLIC_DOMAIN envvar not resolving, add fallback & warning, change Dockerfile interpolation

frontend/astro.config.mjs

@@ -5,6 +5,16 @@ import sitemap from "@astrojs/sitemap";
 
 import react from "@astrojs/react";
 
+// Log warning if RAILWAY_PUBLIC_DOMAIN is not set in production
+if (
+  process.env.NODE_ENV === "production" &&
+  !process.env.RAILWAY_PUBLIC_DOMAIN
+) {
+  console.warn(
+    "⚠️  RAILWAY_PUBLIC_DOMAIN not set in production mode. Falling back to https://dynamic-preauth.xevion.dev"
+  );
+}
+
 // TODO: Add linting to build steps
 
 // https://astro.build/config
@@ -17,10 +27,7 @@ export default defineConfig({
     process.env.NODE_ENV === "development"
       ? "https://localhost:4321"
       : `https://${
-          process.env.RAILWAY_PUBLIC_DOMAIN ??
-          (() => {
-            throw new Error("RAILWAY_PUBLIC_DOMAIN not set");
-          })()
+          process.env.RAILWAY_PUBLIC_DOMAIN || "dynamic-preauth.xevion.dev"
         }`,
   integrations: [
     tailwind(),