修复添加知识报错

src/Hotline.Api/Controllers/KnowledgeController.cs

@@ -175,7 +175,7 @@ namespace Hotline.Api.Controllers
 
             kn.Status = EKnowledgeStatus.Drafts;
             kn.InitId();
-            if (dto.Data.Files.NotNullOrEmpty() == false) kn.FileJson = await _fileRepository.AddFileAsync(dto.Data.Files, kn.Id, "", HttpContext.RequestAborted);
+            if (dto.Data.Files.NotNullOrEmpty()) kn.FileJson = await _fileRepository.AddFileAsync(dto.Data.Files, kn.Id, "", HttpContext.RequestAborted);
             await _knowledgeRepository.AddAsync(kn, HttpContext.RequestAborted);
 
             if (dto.Data.KnowledgeType.Any())