return better default for github cli reader

dist/index.js

@@ -3617,6 +3617,7 @@ class GithubCliReader {
             }
             catch (error) {
                 core.info(error || 'Failed to get github auth token from gh cli');
+                return '';
             }
         });
     }

src/model/input-readers/github-cli.ts

@@ -10,6 +10,7 @@ export class GithubCliReader {
         .replace(/\n/g, '');
     } catch (error: any) {
       core.info(error || 'Failed to get github auth token from gh cli');
+      return '';
     }
   }
 }