How to fix 'Object is possibly null' error when consuming AuthContext in TypeScript?

[ttahasina]

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I am building an authentication system for a React application using TypeScript and the Context API. I've defined my AuthContext and a custom hook useAuth to consume it. However, when I try to use the hook in a component, TypeScript throws an error:
Object is possibly 'null'.
AuthContext.tsx belong code

 import React, { createContext, useContext, useState, ReactNode } from 
'react';
 interface AuthContextType {
  isAuthenticated: boolean;
  user: { id: string; email: string } | null;
  login: (token: string) => void;
  logout: () => void;
 }
 const AuthContext = createContext<AuthContextType | null>(null);
 export const useAuth = () => {
  return useContext(AuthContext)!; 
};
 interface AuthProviderProps {
  children: ReactNode;
 }
 export const AuthProvider: React.FC<AuthProviderProps> = ({ children }) => 
{
  const [isAuthenticated, setIsAuthenticated] = useState(false);
  const [user, setUser] = useState<{ id: string; email: string } | null>
 (null);
const login = (token: string) => {

 setIsAuthenticated(true);
 setUser({ id: '123', email: 'test@example.com' });
 };
 const logout = () => {
 setIsAuthenticated(false);
 setUser(null);
 };
 const value = { isAuthenticated, user, login, logout };
 return <AuthContext.Provider value={value}>{children}
 </AuthContext.Provider>;
 };

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[Gulshan-00]

TypeScript can’t guarantee that your useAuth() hook won’t be called outside of an AuthProvider. So useContext(AuthContext) might return null

export const useAuth = ( ) => {
const context = useContext(AuthContext);
if (!context) {
throw new Error("useAuth must be used within an AuthProvider");
}
return context;
};

This way, if someone tries to use useAuth() without wrapping the component tree in , it’ll throw a clear runtime error instead of causing weird bugs later.

Also, you can remove the non-null assertion "!" since the hook now guarantees a valid context object.

[Rocky-Dewan]

This is a very common and correct TypeScript error when dealing with React Context.
Your context definition:
const AuthContext = createContext<AuthContextType | null>(null);
correctly tells TypeScript that the value inside the context can be AuthContextType OR null.Your hook: return useContext(AuthContext)!; uses the non-null assertion operator (!), which silences the error but is generally discouraged as it hides potential runtime bugs.

Explicit Null Check and Custom Error for solve this issue..

Corrected useAuth Hook

export const useAuth = (): AuthContextType => {
  const context = useContext(AuthContext);

  if (context === null) {
    throw new Error('useAuth must be used within an AuthProvider');
  }

  return context;
};

Refactoring the Context Definition..

const initialAuthContext: AuthContextType = {
  isAuthenticated: false,
  user: null,
  login: () => {}, 
  logout: () => {},
};


const AuthContext = createContext<AuthContextType>(initialAuthContext);

export const useAuth = () => useContext(AuthContext);