feat: make custom network key required

src/app/pages/add-network/add-network.tsx

@@ -49,6 +49,11 @@ export function AddNetwork() {
             setError('Enter a valid URL');
             return;
           }
+          if (!key) {
+            setError('Enter a unique key');
+            return;
+          }
+
           setLoading(true);
           setError('');
           try {

tests-legacy/integration/network/add-network.spec.ts

@@ -44,6 +44,7 @@ describe('Buy tokens test', () => {
 
     it('unable to fetch info from node', async () => {
       await networkPage.inputNetworkAddressField('https://www.google.com/');
+      await networkPage.inputNetworkKeyField('test-network');
       await networkPage.clickAddNetwork();
       await networkPage.waitForErrorMessage();
       const errorMsgElement = await networkPage.page.$$(networkPage.getSelector('$errorText'));