Add firefox xml parsing error

content/posts/2022.12.17.firefox-xml-parsing-error-no-root-element.md

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+---
+title: 'Solving "XML Parsing Error: no root element found" in Firefox'
+date: 2022-12-17T21:27:37-05:00
+toc: false
+images:
+tags:
+  - dev
+  - web 
+---
+
+I've been seeing this error a lot while working on my project [Bulgur Cloud](/bulgur-cloud-intro/).
+It seems to show up only on Firefox:
+
+![Error message in Firefox console. "XML Parsing Error: no root element found. Location: http://...701.jpg Line Number 1, Column 1](/img/2022-12-17.firefox.xml-parsing-error.png)
+
+What is curious was that I was not actually loading the file mentioned in the
+error message. I tried looking up what the error might mean, but all that came
+up was very specific issues regarding some web frameworks, unrelated to what I'm
+using.
+
+I later realized however, while I wasn't loading the file in the error message,
+I was actually sending a `DELETE` request. The Bulgur Cloud server then responds
+to this request with an empty `200 OK` response. Turns out, if you send an empty
+response to Firefox, it tries to parse the body of the response even though it's
+empty and gives you this error.
+
+To quiet this error, I started just sending an empty JSON response even for
+requests that don't actually need it. Here's some rust code to illustrate the
+solution:
+
+```rust
+#[derive(Debug, Serialize)]
+pub struct EmptySuccess {
+    status: &'static str,
+}
+
+// Using actix-web
+fn empty_ok_response() -> HttpResponse {
+    HttpResponse::Ok().json(EmptySuccess { status: "ok"})
+}
+```
+
+This adds a `{"status": "ok"}` json to the response, which seems to be enough to
+make Firefox happy.