Flashing the SD card produces an error about being unreadable

[WillB97]

For Mac:
But this also applies to Windows.

[raccube]

This can actually be turned in to an instruction to click Eject.

[PeterJCLaw]

Does this happen every time? If so, yeah we should mention it and tell users to eject the drive at this point.

[raccube]

Yes, it does - macOS can't read ext4.