Abort the resume when label or comment reads fail

update-pr-stack.sh

@@ -43,8 +43,12 @@ format_state_marker() {
 # Echoes the most recent state-marker line found in our PR comments, or nothing.
 read_state_marker() {
     local PR_NUMBER="$1"
-    gh pr view "$PR_NUMBER" --json comments --jq '.comments[].body' 2>/dev/null \
-        | { grep -F "$STATE_MARKER_PREFIX" || true; } | tail -n1
+    local BODIES
+    if ! BODIES=$(gh pr view "$PR_NUMBER" --json comments --jq '.comments[].body'); then
+        echo "Error: could not read comments of PR #$PR_NUMBER" >&2
+        exit 1
+    fi
+    { grep -F "$STATE_MARKER_PREFIX" <<<"$BODIES" || true; } | tail -n1
 }
 
 # Args: a marker line. Echoes "base target squash".
@@ -231,11 +235,14 @@ See $GITHUB_SERVER_URL/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID"
     return 0
 }
 
-# Check if a PR has the conflict resolution label
+# Check if a PR has the conflict resolution label.
 pr_has_conflict_label() {
     local PR_NUMBER="$1"
     local LABELS
-    LABELS=$(gh pr view "$PR_NUMBER" --json labels --jq '.labels[].name' 2>/dev/null || echo "")
+    if ! LABELS=$(gh pr view "$PR_NUMBER" --json labels --jq '.labels[].name'); then
+        echo "Error: could not read labels of PR #$PR_NUMBER" >&2
+        exit 1
+    fi
     echo "$LABELS" | grep -q "^${CONFLICT_LABEL}$"
 }