Aggregation error insufficient batch size 0

[carlweng]

I'm running the prototype in a Ubuntu Linux server.

The command cargo run --bin leader returns:

Finished dev [unoptimized + debuginfo] target(s) in 0.51s
Running `target/debug/leader`

The command cargo run --bin helper returns:

Finished dev [unoptimized + debuginfo] target(s) in 0.10s
Running `target/debug/helper`

The command cargo run --bin client is executed several times and it typically returns:

Finished dev [unoptimized + debuginfo] target(s) in 0.09s
Running `target/debug/client`

However, when the command cargo run --bin collector is executed, it returns

Finished dev [unoptimized + debuginfo] target(s) in 0.09s
Running `target/debug/collector`
Error:
0: HTTP problem document 400 Bad Request - Aggregation error insufficient batch size 0

Location:
src/bin/collector.rs:18

Backtrace omitted.
Run with RUST_BACKTRACE=1 environment variable to display it.
Run with RUST_BACKTRACE=full to include source snippets.

The leader side also show errors including "Aggregation error insufficient batch size 0".
Do you have any clue why this would happen.

Thank you in advance!