Aliases to `void` are converted to `null`

[dansteren]

Given the following canister

type VoidAlias = Alias<void>;

$query;
export function voidAliasTest(): VoidAlias {}

When running dfx deploy Then the following candid file is expected to be generated:

service : () -> { voidAliasTest : () -> () query }

Currently, it actually generates:

service : () -> { voidAliasTest : () -> (null) query }

Note There is a broken test for this in the rust_type_conversions example that should be updated as part of this ticket.

[bdemann]

Important With how aliases for void are done right now this is technically not a problem. The problematic code still exists but it shouldn't ever run because aliases to void just get replaced with void thanks the the alias table. When this issue https://github.com/demergent-labs/azle/issues/1118 is resolved I suspect that this ticket will become an issue again.

[lastmjs]

We should check to make sure we can do the equivalent in Azle 0.18+