ExistentialDeposit: PlainDescriptor<bigint>

The minimum amount required to keep an account open. MUST BE GREATER THAN ZERO!

If you really need it to be zero, you can enable the feature insecure_zero_ed for this pallet. However, you do so at your own risk: this will open up a major DoS vector. In case you have multiple sources of provider references, you may also get unexpected behaviour if you set this to zero.

Bottom line: Do yourself a favour and make it at least one!