Why does it give an error cannot read propery of undefined?

Question

React

Hello everyone,
I just started learning React and ran into this problem. I receive data from the server (menu), the request returns the data correctly. Further through mapStateToProps I pass it to the props, in the console of the component the property is displayed normally. But if I try to call the map method in the renderer, then I get an error that it cannot read from undefined. If you call the log, then the properties of the component are displayed before rendering, and undefined when rendering. I can't understand why.

Answer 1

Apparently, you do not set an empty array items in initialState or destroy it in the reducer in the FETCH_MENU case . Can't say for sure without the reducer code. But I think that's the point. For the future. Attach code examples to the question, not screenshots. And examples of exactly the code that causes the error, and not some other.