Fix sortAsc crash when set contains commits not in the DAG

Summary:
During drag-and-drop rebase previews, the preview DAG may contain
optimistic commits (e.g. OPTIMISTIC_REBASE_SUCC: hashes) that are not
present in the cached defaultSortAscIndex. Previously this threw
"not in the dag" errors.

Instead of silently filtering out missing commits (which would lose them
from the sorted output), fall back to the full topological sortAsc on
the underlying commitDag when any hash in the set is missing from the
cached index. This preserves all commits in the output while avoiding
the crash.

Fixes #1229

Differential Revision: D99703453

fbshipit-source-id: 3ccfc17ffa1a88ced16c8b700d72ffcb70fb6fec

Author: bherila

addons/isl/src/dag/dag.ts

@@ -273,14 +273,14 @@ export class Dag extends SelfUpdate<CommitDagRecord> {
       if (set === undefined) {
         return [...sorted];
       }
-      const hashes = arrayFromHashes(set === undefined ? this.all() : set);
+      const hashes = arrayFromHashes(set);
+      if (hashes.some(h => !index.has(h))) {
+        // Fall back to full topological sort when set contains commits not in
+        // the cached index (e.g. optimistic rebase preview commits).
+        return this.commitDag.sortAsc(set, {compare: sortAscCompare});
+      }
       return hashes.sort((a, b) => {
-        const aIdx = index.get(a);
-        const bIdx = index.get(b);
-        if (aIdx == null || bIdx == null) {
-          throw new Error(`Commit ${a} or ${b} is not in the dag.`);
-        }
-        return aIdx - bIdx;
+        return (index.get(a) as number) - (index.get(b) as number);
       });
     }
     // Otherwise, fallback to sortAsc.