If You're using JSX inside a function with curly braces you need to modify it to parenthesis.
Wrong Code
return this.props.todos.map((todo) => {
<h3> {todo.author} </h3>;
});
Correct Code
//Change Curly Brace To Paranthesis change {} to => ()
return this.props.todos.map((todo) => (
<h3> {todo.author} </h3>;
));