Fix "Error: No request context set" in credentials fixture (#145)

Make sure that we've run the `context` fixture first, so that the request API
is configured

Author: richvdh

packages/element-web-playwright-common/src/fixtures/user.ts

@@ -70,7 +70,11 @@ export const test = base.extend<{
     user: Credentials;
 }>({
     displayName: undefined,
-    credentials: async ({ homeserver, displayName: testDisplayName }, use, testInfo) => {
+
+    // We don't directly depend upon the `context` fixture, but we do need to make sure that it has been run
+    // before this fixture, since it is responsible for configuring the APIRequestContext on the homeserver, so
+    // without it we cannot register the user.
+    credentials: async ({ context, homeserver, displayName: testDisplayName }, use, testInfo) => {
         const names = ["Alice", "Bob", "Charlie", "Daniel", "Eve", "Frank", "Grace", "Hannah", "Isaac", "Judy"];
         const password = uniqueId("password_");
         const displayName = testDisplayName ?? sample(names)!;