Use ServerError provided by Context (#14333)

... instead of InternalServerError by macaron

routers/repo/issue.go

@@ -1117,7 +1117,7 @@ func ViewIssue(ctx *context.Context) {
 		iw.IssueID = issue.ID
 		iw.IsWatching, err = models.CheckIssueWatch(ctx.User, issue)
 		if err != nil {
-			ctx.InternalServerError(err)
+			ctx.ServerError("CheckIssueWatch", err)
 			return
 		}
 	}