사용자 초대 모달에서 에러가 발생했습니다.

import fetcher from '@utils/fetcher';
import axios from 'axios';
import React, { VFC, useCallback, useState } from 'react';
import { Redirect, Route, Switch, useParams } from 'react-router';
import useSWR from 'swr';

import {
  Header,
  ProfileImg,
  RightMenu,
  WorkspaceWrapper,
  WorkspaceName,
  Workspaces,
  Channels,
  Chats,
  MenuScroll,
  ProfileModal,
  LogOutButton,
  WorkspaceButton,
  AddButton,
  WorkspaceModal,
} from './styles';
import gravatar from 'gravatar';
import loadable from '@loadable/component';
import Menu from '@components/Menu';

const Channel = loadable(() => import('@pages/Channel'));
const DirectMessage = loadable(() => import('@pages/DirectMessage'));
import { Link } from 'react-router-dom';
import { IChannel, IUser } from '@typings/db';
import Modal from '@components/Modal';
import { Button, Input, Label } from '@pages/SignUp/styles';
import useInput from '@hooks/useInput';
import { toast } from 'react-toastify';
import CreateChannelModal from '@components/CreateChannelModal';
import InviteWorkspaceModal from '@components/InviteWorkspaceModal';
import InviteChannelModal from '@components/InviteChannelModal';
// import ChannelList from '@components/ChannelList';
import DMList from '@components/DMList';
import ChannelList from '@components/ChannelList';

// FC타입안에 children이 알아서 들어있음
// children 안쓸거면 VFC
const Workspace: VFC = () => {
  const [showUserMenu, setShowUserMenu] = useState(false);
  const [showCreateWorkspaceModal, setShowCreateWorkspaceModal] = useState(false);
  const [showInviteWorkspaceModal, setShowInviteWorkspaceModal] = useState(false);
  const [showInviteChannelModal, setShowInviteChannelModal] = useState(false);
  const [newWorkspace, onChangeNewWorkspace, setNewWorkspace] = useInput('');
  const [newUrl, onChangeNewUrl, setNewUrl] = useInput('');
  const [showWorkspaceModal, setShowWorkspaceModal] = useState(false);
  const [ShowCreateChannelModal, setShowCreateChannelModal] = useState(false);

  const { workspace } = useParams<{ workspace: string }>();
  // 사용자 데이터 가져오기
  const {
    data: userData,
    error,
    revalidate,
    mutate,
  } = useSWR<IUser | false>('/api/users', fetcher, {
    dedupingInterval: 2000,
  });

  // channel 데이터 가져오기
  const { data: channelData } = useSWR<IChannel[]>(userData ? `/api/workspaces/${workspace}/channels` : null, fetcher);

  // 워크스페이스에 있는 멤버 데이터
  const { mutate: revalidateMembers } = useSWR<IUser[]>(
    userData ? `/api/workspaces/${workspace}/members` : null,
    fetcher,
  );

  // 로그아웃
  const onLogout = useCallback(() => {
    axios
      .post('/api/users/logout', null, {
        withCredentials: true,
      })
      .then((response) => {
        mutate(response.data);
        // 기존에 받은 데이터를 mutate의 data에 담음
      })
      .catch((error) => {
        console.log(error);
      });
  }, []);
  // 프로필 누르면 메뉴 보이기
  const onClickUserProfile = useCallback(() => {
    setShowUserMenu((prev) => !prev);
  }, []);
  // 프로필 닫기
  const onCloseUserProfile = useCallback((e) => {
    e.stopPropagation();
    setShowUserMenu(false);
  }, []);
  // 워크스페이스 모달 열기
  const onClickCreateWorkspace = useCallback(() => {
    setShowCreateWorkspaceModal(true);
  }, []);

  // 워크스페이스 모달 닫기
  const onCloseModal = useCallback(() => {
    setShowCreateWorkspaceModal(false);
    setShowCreateChannelModal(false);
    setShowInviteChannelModal(false);
    setShowInviteWorkspaceModal(false);
  }, []);
  // 워크스페이스 생성
  const onCreateWorkspace = useCallback(
    (e) => {
      e.preventDefault();
      // trim() 안넣으면 띄어쓰기 넣으면 걍 통과됨

      if (!newWorkspace || !newWorkspace.trim()) return;
      if (!newUrl || !newUrl.trim()) return;
      axios
        .post(
          '/api/workspaces',
          {
            workspace: newWorkspace,
            url: newUrl,
          },
          {
            withCredentials: true,
          },
        )
        .then(() => {
          revalidate();
          setShowCreateWorkspaceModal(false);
          setNewWorkspace('');
          setNewUrl('');
        })
        .catch((error) => {
          console.log(error);
          toast.error(error.response?.data, { position: 'bottom-center' });
        });
    },
    [newWorkspace, newUrl],
  );
  // 워크스페이스 사용자 초대
  const onClickInviteWorkspace = useCallback(() => {
    setShowInviteWorkspaceModal(true);
  }, []);
  // Channel

  // 토글
  const toggleWorkspaceModal = useCallback(() => {
    setShowWorkspaceModal((prev) => !prev);
  }, []);

  // 채널 만들기
  const onClickAddChannel = useCallback(() => {
    setShowCreateChannelModal(true);
  }, []);

  if (!userData) {
    return <Redirect to="/login" />;
  }

  return (
    <div>
      <Header>
        <RightMenu>
          <span onClick={onClickUserProfile}>
            <ProfileImg src={gravatar.url(userData.nickname, { s: '28px', d: 'retro' })} alt={userData.nickname} />
            {showUserMenu && (
              <Menu style={{ right: 0, top: 38 }} show={showUserMenu} onCloseModal={onCloseUserProfile}>
                <ProfileModal>
                  <img src={gravatar.url(userData.nickname, { s: '36px', d: 'retro' })} alt={userData.nickname} />
                  <div>
                    <span id="profile-name">{userData.nickname}</span>
                    <span id="profile-active">Active</span>
                  </div>
                </ProfileModal>
                <LogOutButton onClick={onLogout}>로그아웃</LogOutButton>
              </Menu>
            )}
          </span>
        </RightMenu>
      </Header>
      <WorkspaceWrapper>
        <Workspaces>
          {userData?.Workspaces.map((ws) => {
            return (
              <Link key={ws.id} to={`/workspace/${123}/channel/일반`}>
                <WorkspaceButton>{ws.name.slice(0, 1).toUpperCase()}</WorkspaceButton>
              </Link>
            );
          })}
          <AddButton onClick={onClickCreateWorkspace}>+</AddButton>
        </Workspaces>
        <Channels>
          <WorkspaceName onClick={toggleWorkspaceModal}>Sleact</WorkspaceName>
          <MenuScroll>
            <Menu show={showWorkspaceModal} onCloseModal={toggleWorkspaceModal} style={{ top: 95, left: 80 }}>
              <WorkspaceModal>
                <h2>Sleact</h2>
                <button onClick={onClickInviteWorkspace}>워크스페이스에 사용자 초대</button>
                <button onClick={onClickAddChannel}>채널 만들기</button>
                <button onClick={onLogout}>로그아웃</button>
              </WorkspaceModal>
            </Menu>
            <ChannelList />
            <DMList />
            {/* {channelData?.map((v) => (
              <div>{v.name}</div>
            ))} */}
          </MenuScroll>
        </Channels>
        <Chats>
          <Switch>
            <Route path="/workspace/:workspace/channel/:channel" component={Channel} />
            <Route path="/workspace/:workspace/dm/:id" component={DirectMessage} />
          </Switch>
        </Chats>
      </WorkspaceWrapper>
      <Modal show={showCreateWorkspaceModal} onCloseModal={onCloseModal}>
        <form onSubmit={onCreateWorkspace}>
          <Label id="workspace-label">
            <span>워크스페이스 이름</span>
            <Input id="workspace" value={newWorkspace} onChange={onChangeNewWorkspace} />
          </Label>
          <Label id="workspace-url-label">
            <span>워크스페이스 url</span>
            <Input id="workspace" value={newUrl} onChange={onChangeNewUrl} />
          </Label>
          <Button type="submit">생성하기</Button>
        </form>
      </Modal>
      <CreateChannelModal
        show={ShowCreateChannelModal}
        onCloseModal={onCloseModal}
        setShowCreateChannelModal={setShowCreateChannelModal}
      />
      <InviteWorkspaceModal
        show={showInviteWorkspaceModal}
        onCloseModal={onCloseModal}
        setShowInviteWorkspaceModal={setShowInviteWorkspaceModal}
      />
      <InviteChannelModal
        show={showInviteChannelModal}
        onCloseModal={onCloseModal}
        setShowInviteChannelModal={setShowInviteChannelModal}
      />
    </div>
  );
};

export default Workspace;

이건 제가 작성한 WorkSpace 입니다.

import Modal from '@components/Modal';
import useInput from '@hooks/useInput';
import { Button, Input, Label } from '@pages/SignUp/styles';
import { IUser } from '@typings/db';
import fetcher from '@utils/fetcher';
import axios from 'axios';
import React, { FC, useCallback } from 'react';
import { useParams } from 'react-router';
import { toast } from 'react-toastify';
import useSWR from 'swr';

interface Props {
  show: boolean;
  onCloseModal: () => void;
  setShowInviteChannelModal: (flag: boolean) => void;
}
const InviteChannelModal: FC<Props> = ({ show, onCloseModal, setShowInviteChannelModal }) => {
  const { workspace, channel } = useParams<{ workspace: string; channel: string }>();
  const [newMember, onChangeNewMember, setNewMember] = useInput('');
  const { data: userData } = useSWR<IUser>('/api/users', fetcher);
  const { revalidate: revalidateMembers } = useSWR<IUser[]>(
    userData ? `/api/workspaces/${workspace}/channels/${channel}/members` : null,
    fetcher,
  );
  console.dir(channel);
  const onInviteMember = useCallback(
    (e) => {
      e.preventDefault();
      if (!newMember || !newMember.trim()) {
        return;
      }
      axios
        .post(`/api/workspaces/${workspace}/channels/${channel}/members`, {
          email: newMember,
        })
        .then(() => {
          revalidateMembers();
          setShowInviteChannelModal(false);
          setNewMember('');
        })
        .catch((error) => {
          console.dir(error);
          toast.error(error.response?.data, { position: 'bottom-center' });
        });
    },
    [channel, newMember, revalidateMembers, setNewMember, setShowInviteChannelModal, workspace],
  );

  return (
    <Modal show={show} onCloseModal={onCloseModal}>
      <form onSubmit={onInviteMember}>
        <Label id="member-label">
          <span>채널 멤버 초대</span>
          <Input id="member" value={newMember} onChange={onChangeNewMember} />
        </Label>
        <Button type="submit">초대하기</Button>
      </form>
    </Modal>
  );
};

export default InviteChannelModal;

이건 제가 작성한 InviteChannelModal입니다.

xhr.js:210     GET http://localhost:3090/api/workspaces/sleact/channels/undefined/members 404 (Not Found)
dispatchXhrRequest @ xhr.js:210
xhrAdapter @ xhr.js:15
dispatchRequest @ dispatchRequest.js:58
request @ Axios.js:108
Axios.<computed> @ Axios.js:129
wrap @ bind.js:9
fetcher @ fetcher.ts:18
eval @ use-swr.js:392
step @ use-swr.js:43
eval @ use-swr.js:24
eval @ use-swr.js:18
__awaiter @ use-swr.js:14
eval @ use-swr.js:344
softRevalidate @ use-swr.js:532
onFocus @ use-swr.js:550
revalidate_1 @ use-swr.js:73
eval @ use-swr.js:77
eval @ web-preset.js:29

그런데 위와 같은 에러가 발생합니다.

콘솔에 channel을 출력해도 undefined가 뜹니다.. 그런데 url을 보면 http://localhost:3090/workspace/sleact/channel/테스트채널 이렇게 채널 명이 표시가 되는데 도대체 뭐 때문에 undefined라고 뜨는지 모르겠습니다... 아무리 찾아봐도 알 수가 없어서 글 남깁니다... 분명 WorkSpace의 route에도 오타가 없고 url도 표시가 잘되는데 왜 undefined일까요...