JavaScript warnings on Array, Object-type methods does not respect function parameter defaults #73

Using this example code below:

_renderAttachments(attachments = []) {
    return attachments.map((attach) => {

DeepCode will warn that calling .map() on non array object for attachments will not work.
It suggests to use (attachments || []). While this is correct, it does not account for the function parameter default value which is already provided.

In the above case, the function already provides a fallback for (attachments = []), so the suggested change would offer no further benefit.

This also occurs for things like Object fallbacks (attachments = {}), or es6 Object types such as (attachments = new Map())