Turn a possible panic into an error message that will help to debug it. (#9886)

* Turn a possible panic into an error message that will help to debug it.

* Make `d o t` available to everyone to ease debugging.

The disadvantage is that we then launch`dot`, assuming it is the program we know
to create an SVG, and we write a file to disk.
It should, however, be hard to trigger by accident, and I'd assume calling
this won't destroy anything.

Author: Byron

crates/but-graph/src/init/post.rs

@@ -4,7 +4,7 @@ use crate::init::walk::{RefsById, disambiguate_refs_by_branch_metadata};
 use crate::init::{PetGraph, branch_segment_from_name_and_meta, remotes};
 use crate::projection::workspace;
 use crate::{Commit, CommitFlags, CommitIndex, Edge, Graph, SegmentIndex, SegmentMetadata};
-use anyhow::bail;
+use anyhow::{Context as _, bail};
 use but_core::{RefMetadata, ref_metadata};
 use gix::prelude::ObjectIdExt;
 use gix::reference::Category;
@@ -176,7 +176,17 @@ impl Graph {
         meta: &OverlayMetadata<'_, T>,
     ) -> anyhow::Result<SegmentIndex> {
         let s = &mut self[sidx];
-        let tip_of_new_segment = s.commits[cidx_for_new_segment].id;
+        let tip_of_new_segment = s
+            .commits
+            .get(cidx_for_new_segment)
+            .with_context(|| {
+                format!(
+                    "Segment {sidx:?} \
+        has only {} commit(s), cannot split at {cidx_for_new_segment}",
+                    s.commits.len()
+                )
+            })?
+            .id;
         let new_segment_commits = s.commits.drain(cidx_for_new_segment..).collect();
         let last_cidx_in_top_segment = s.last_commit_index();
         let edges_to_reconnect: Vec<_> = self

crates/gitbutler-tauri/src/main.rs

@@ -332,7 +332,7 @@ fn main() {
                     // Debug-only - not for production!
                     #[cfg(debug_assertions)]
                     env::env_vars,
-                    #[cfg(all(debug_assertions, unix))]
+                    #[cfg(unix)]
                     workspace::show_graph_svg,
                     claude::claude_send_message,
                     claude::claude_get_messages