MutationObserver.observe() should not have optional second argument

[diesal11]

According to MutationObserver MDN docs, calling .observe() without an options argument will throw a type error.

The docs for the options type MutationObserverInit state that:

At a minimum, one of childList, attributes, and/or characterData must be true when you call observe(). Otherwise, a TypeError exception will be thrown.

However, all of childList, attributes & characterData are false by default, including when an options argument is not provided. Therefore i believe that the secondary argument for observe() being optional is incorrect.

[felipe-sme]

Yep, Typescript marks the MutationObserver observe method signature as MutationObserver.observe(target: Node, options?: MutationObserverInit): void. Calling it without an options object doesn't give you a static error, but you'll get a runtime type error as it isn't optional. At least one of the properties needs to be passed in as true.