Clean up DnD shared prompt asset tests

internal/cli/run_test.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -208,6 +209,15 @@ func TestProductionPromptAssetsRegisterAndPrepareDndPrompts(t *testing.T) {
 			t.Fatalf("PromptFS().Open(%q) error = %v, want nil", name, err)
 		}
 	}
+	for _, name := range []string{
+		"common-dnd-system.md",
+		"common-dnd-transcript.md",
+		"common-dnd-references.md",
+	} {
+		if _, err := promptFS.Open(name); !errors.Is(err, fs.ErrNotExist) {
+			t.Fatalf("PromptFS().Open(%q) error = %v, want not exist", name, err)
+		}
+	}
 
 	options, err := registry.ScriptoriumOptions()
 	if err != nil {