:sparkles: Return an error when components and applications are used outside of a browser-like environment.

1 files changed, 11 insertions, 1 deletions

diff --git a/lib/src/lustre.ffi.mjs b/lib/src/lustre.ffi.mjs
index 998c598..5cf5058 100644
--- a/lib/src/lustre.ffi.mjs
+++ b/lib/src/lustre.ffi.mjs
@@ -1,4 +1,8 @@
-import { ElementNotFound, ComponentAlreadyRegistered } from "./lustre.mjs";
+import {
+  ElementNotFound,
+  ComponentAlreadyRegistered,
+  NotABrowser,
+} from "./lustre.mjs";
 import { from } from "./lustre/effect.mjs";
 import { map } from "./lustre/element.mjs";
 import { morph } from "./runtime.ffi.mjs";
@@ -26,6 +30,7 @@ export class App {
   }
 
   start(selector, flags) {
+    if (!is_browser()) return new Error(new NotABrowser());
     if (this.#root) return this;
 
     try {
@@ -137,6 +142,7 @@ export const setup_component = (
   render,
   on_attribute_change
 ) => {
+  if (!is_browser()) return new Error(new NotABrowser());
   if (customElements.get(name)) {
     return new Error(new ComponentAlreadyRegistered());
   }
@@ -204,3 +210,7 @@ export const setup_component = (
   );
   return new Ok(null);
 };
+
+// UTLS ------------------------------------------------------------------------
+
+export const is_browser = () => window && window.document;