There is a type that is quite interesting in typescript void | {}, this type has some unique behavior, everything can be assigned to this type, but the compiler does not infer any property for this type unlike for {} that inherits the basic object properties, the difference with {} is subtile but still pretty interesting:

function func1(val: {} ) {
    val.hasOwnProperty('hello'); // no error
}
function func2(val: {} | void) {
    val.hasOwnProperty('hello');  // error:  Property 'hasOwnProperty' does not exist on type 'void | {}'.
}

However there is not typeguard for void, it could be interesting to add some type guards for this case:

• typeof val !== 'undefined'
• val !== undefined
• val != undefined
• val != null