Fix a bug where HTTP errors where being reported incorrectly (#18828)

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/gpui/src/app.rs

@@ -1533,4 +1533,8 @@ impl HttpClient for NullHttpClient {
     fn proxy(&self) -> Option<&http_client::Uri> {
         None
     }
+
+    fn type_name(&self) -> &'static str {
+        type_name::<Self>()
+    }
 }