react-error-overlay showing up only in Firefox

[mic4ael]

I have a few questions about the react-error-overlay (6.0.9).

1. Is it true that it is only displayed when the developer console is open?
2. Does it only work in Firefox? The overlay seems to be displayed only in Firefox.

I navigated the code of the package but I couldn't find anything that would help me understand why it works like that.