Replace fetch with Axios in client

Replace `.then` with await syntax where possible.

GitLab: #142
Change-Id: I6c132f49f152afa7e20919a1c70c539f2ad54878
diff --git a/client/src/utils/constants.ts b/client/src/utils/constants.ts
index f5c5423..56c738a 100644
--- a/client/src/utils/constants.ts
+++ b/client/src/utils/constants.ts
@@ -21,4 +21,10 @@
 
 export const jamiLogoDefaultSize = '512px';
 
-export const apiUrl = new URL(import.meta.env.VITE_API_URL);
+const apiUrl: string = import.meta.env.VITE_API_URL;
+
+if (!apiUrl) {
+  throw new Error('VITE_API_URL not defined');
+}
+
+export { apiUrl };