Errors because of omitting ;

example.js

/**************************************************
 * Immediatly executing anonymous function
 **************************************************/

// Results in error "TypeError: console.log(...) is not a function"

console.log('example')
(async () => {})()

// With using of ; it works

console.log('example');
(async () => {})()

/**************************************************
 * Destructioning
 **************************************************/

// Results in error "ReferenceError: c is not defined"

let a, b
const c = [1, 2]
[a, b] = c

// With using of ; it works

let a, b
const c = [1, 2];
[a, b] = c

A detailed article about the automatic semicolon insertion (ASI) feature: http://inimino.org/~inimino/blog/javascript_semicolons

A good remember to avoid the problems:
just remember to start lines with ; when they start with [ or (

So the both use cases would looks like:

// Immediatly executing anonymous function

console.log('example')
;(async () => {})()

// Destructioning

let a, b
const c = [1, 2]
;[a, b] = c