Check for missing addListener (#37)

* Check for missing addListener

* Bump version

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@sats-connect/core",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "main": "dist/index.mjs",
   "module": "dist/index.mjs",
   "types": "dist/index.d.mts",

src/request/index.ts

@@ -63,6 +63,17 @@ export const addListener = (
     throw new Error('no wallet provider was found');
   }
 
+  // Clients may have be using the latest version of sats-connect without their
+  // wallets having been updated. Until we have API versioning for the wallet,
+  // we can avoid having apps crash by checking whether the adapter actually
+  // supports `addListener`.
+  if (!provider.addListener) {
+    console.error(
+      `The wallet provider you are using does not support the addListener method. Please update your wallet provider.`
+    );
+    return () => {};
+  }
+
   return provider.addListener(event, cb);
 };