fix: scale up lambda build issue. (#3388)

Author: GuptaNavdeep1983

Diff for: lambdas/functions/control-plane/src/scale-runners/scale-up.ts

@@ -212,7 +212,7 @@ export async function scaleUp(eventSource: string, payload: ActionRequestMessage
   if (eventSource !== 'aws:sqs') throw Error('Cannot handle non-SQS events!');
   const enableOrgLevel = yn(process.env.ENABLE_ORGANIZATION_RUNNERS, { default: true });
   const maximumRunners = parseInt(process.env.RUNNERS_MAXIMUM_COUNT || '3');
-  const runnerLabels = process.env.RUNNER_LABELS;
+  const runnerLabels = process.env.RUNNER_LABELS || '';
   const runnerGroup = process.env.RUNNER_GROUP_NAME || 'Default';
   const environment = process.env.ENVIRONMENT;
   const ghesBaseUrl = process.env.GHES_URL;