fix(#2752): pr-status must not abort on a repo with no CI

On a repo with no CI configured forgejo returns the combined-status
`statuses` field as an explicit `null` rather than `[]`.
`#[serde(default)]` only covers a *missing* key — a present null still
fails to deserialize, so `pr-status` died with
`invalid type: null, expected a sequence` instead of reporting the PR.

Deserialize the field through an `Option<Vec<_>>` so both null and
absent map to an empty vec.

Closes #2752.

hive-forge/src/verbs/pr_status.rs

@@ -12,6 +12,7 @@
 use anyhow::{Context, Result, bail};
 use clap::Args as ClapArgs;
 use forgejo_api::structs::IssueGetCommentsQuery;
+use serde::Deserialize;
 use serde_json::Value;
 
 use crate::client::{Client, index};
@@ -53,14 +54,29 @@ pub fn run(client: &Client, args: Args) -> Result<()> {
 /// Keeping `state` a plain `String` (and the per-context statuses as
 /// opaque `Value`s, which the render helpers already walk) means an
 /// unknown or empty state is reported rather than fatal.
+///
+/// `statuses` needs the same leniency for a different reason: on a repo
+/// with no CI at all the field comes back as an explicit `null` rather
+/// than `[]`, and `#[serde(default)]` only covers a *missing* key — a
+/// present null still fails to deserialize. So a doc-only repo makes the
+/// whole verb error out on exactly the PRs where "no CI here" is the
+/// answer worth printing.
 #[derive(serde::Deserialize, Default)]
 pub(crate) struct CombinedStatus {
     #[serde(default)]
     pub state: String,
-    #[serde(default)]
+    #[serde(default, deserialize_with = "null_as_empty")]
     pub statuses: Vec<Value>,
 }
 
+/// Deserialize a possibly-null JSON array as an empty `Vec`.
+fn null_as_empty<'de, D>(de: D) -> Result<Vec<Value>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    Ok(Option::<Vec<Value>>::deserialize(de)?.unwrap_or_default())
+}
+
 /// CI-only path for an explicit commit. Exit code mirrors the CI verdict.
 fn sha_status(client: &Client, sha: &str) -> Result<()> {
     let (state, statuses) = fetch_combined(client, sha)?;
@@ -413,6 +429,15 @@ mod tests {
         assert!(c.statuses.is_empty());
     }
 
+    #[test]
+    fn combined_status_tolerates_null_statuses() {
+        // A repo with no CI configured: the field is present and null,
+        // which `#[serde(default)]` alone does not cover.
+        let c: CombinedStatus =
+            serde_json::from_str(r#"{"state":"","statuses":null,"sha":"abc"}"#).unwrap();
+        assert!(c.statuses.is_empty());
+    }
+
     #[test]
     fn combined_json_shape() {
         let v = combined_json("abc", "success", &[]);