Fix preview crashing when token do not include site data (GitbookIO#2292)

Author: spastorelli

src/middleware.ts

@@ -485,13 +485,19 @@ async function lookupSpaceInMultiIdMode(request: NextRequest, url: URL): Promise
  }
 
  const decoded = jwt.decode(apiToken) as ContentAPITokenPayload;
+ const siteLookupResult =
+ typeof decoded.site === 'string' &&
+ decoded.site &&
+ typeof decoded.organization === 'string' &&
+ decoded.organization
+ ? { site: decoded.site, organization: decoded.organization }
+ : {};
 
  return {
  space: spaceId,
  changeRequest: changeRequestId,
  revision: revisionId,
- site: decoded.site,
- organization: decoded.organization,
+ ...siteLookupResult,
  basePath: normalizePathname(basePathParts.join('/')),
  pathname: normalizePathname(pathSegments.join('/')),
  apiToken,