test(reconcile): a verdict returned with an error is not used

Mutation-testing showed the forced-unsure line was untested because my fake
always returned unsure with its errors.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/reconcile/reconcile_test.go

@@ -277,3 +277,17 @@ func TestReconcile_ContestedSpotsAreCappedButTheCountsAreExact(t *testing.T) {
 	assert.Equal(t, 300, out.Reconciliation.Disputes)
 	assert.Len(t, out.Reconciliation.Contested, reconcile.MaxContested, "the stored list is bounded; the counts are not")
 }
+
+func TestReconcile_AVerdictReturnedAlongsideAnErrorIsIgnored(t *testing.T) {
+	// An adjudicator that returns a verdict AND an error must not have the verdict used:
+	// the contract is that an error means no decision.
+	adj := &scripted{fn: func(int, reconcile.Request) (reconcile.Verdict, error) {
+		return reconcile.VerdictAlt, errors.New("half a reply")
+	}}
+
+	out := merge(t, tr("a x b"), tr("a y b"), adj)
+
+	assert.Equal(t, "a x b", out.Text, "no decision means the base stands")
+	assert.Zero(t, out.Reconciliation.Changed)
+	assert.Equal(t, 1, out.Reconciliation.Unsure)
+}