无法读取未定义的属性“0”

Question

After signing in using facebook, this happens:

Server running on port: 5000

GET / 304 28.608 ms - -

GET /auth/facebook 302 5.910 ms - 0

events.js:160
      throw er; // Unhandled 'error' event
  ^

TypeError: Cannot read property '0' of undefined
    at C:\Users\dhouha\node-js-getting-started\config\passport.js:90:49
    at Query.<anonymous> (C:\Users\dhouha\node-js-getting-started\node_modules\mongoose\lib\model.js:3433:16)
    at C:\Users\dhouha\node-js-getting-started\node_modules\kareem\index.js:273:21
    at C:\Users\dhouha\node-js-getting-started\node_modules\kareem\index.js:127:16
    at _combinedTickCallback (internal/process/next_tick.js:67:7)
    at process._tickCallback (internal/process/next_tick.js:98:9)

Answer 1

Your program is trying to access the first element of some array (first element with index 0) but it is undefined.

Search your code for something[0] in line 90 of:

• C:\\Users\\dhouha\\node-js-getting-started\\config\\passport.js

and try to figure out why the array used there is undefined.