Improve env var handling for nameguard-js (#382)

* Improve env var handling for nameguard-js

.changeset/large-pumas-call.md

@@ -0,0 +1,5 @@
+---
+"@namehash/nameguard-js": patch
+---
+
+Refine nameguard-js unit tests

.github/workflows/typescript-packages-unit-tests.yml

@@ -12,6 +12,10 @@ on:
     paths:
       - "packages/**"
 
+env:
+  PROVIDER_URI_MAINNET: ${{ secrets.PROVIDER_URI_MAINNET }}
+  PROVIDER_URI_SEPOLIA: ${{ secrets.PROVIDER_URI_SEPOLIA }}
+
 jobs:
   test:
     strategy:

packages/nameguard-js/src/nameguard-js.test.ts

@@ -6,6 +6,18 @@ import { createClient } from "./nameguard-js";
 const PROVIDER_URI_MAINNET = process.env.PROVIDER_URI_MAINNET;
 const PROVIDER_URI_SEPOLIA = process.env.PROVIDER_URI_SEPOLIA;
 
+if (!PROVIDER_URI_MAINNET) {
+  throw new Error(
+    "The PROVIDER_URI_MAINNET environment variable is not defined.",
+  );
+}
+
+if (!PROVIDER_URI_SEPOLIA) {
+  throw new Error(
+    "The PROVIDER_URI_SEPOLIA environment variable is not defined.",
+  );
+}
+
 /**
  * This is a fake endpoint that will not work.
  * If a client created with this endpoint tries to make an API request, it will throw an error.