deleting value return null insteed of undefined

[thib3113]

A non existing value return "undefined", where deleting a value just replace the value by "null", so getting the deleted value return null .

I've done some research in the code, and in fact, I doesn't understand this line :
https://github.com/cayasso/cacheman-memory/blob/master/src/index.js#L39
if (data.expire !== -1 && data.expire < Date.now()) {

To remove a value, you set the data.expire to -1, so why checking if data.expire !== -1 to delete it ?
I think, this line need to be :
if (data.expire === -1 || data.expire < Date.now()) {

Or directly
if (data.expire < Date.now()) {

Else, the deleted value (replaced by null), is returned ...

[thib3113]

This break the test should not expire key ... But why the key doesn't need to not expire ? If I delete the key, I wont to remove the key too ? no ?

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edit :
Ok, after some search in commit I see, it's to keep some cache without TTL ... But, so when the key is deleted, you need to pass something else .. ( not -1, something like -2 ? )