Handle null value for viewId in nextArgs GraphQL query

[sandreae]

Currently we attempt to parse a null value into a DocumentViewIdScalar which correctly fails, but we would rather continue the request understanding no view id was assigned.

This is a behaviour change introduced when moving to use async-graphql dynamic module and should be reverted.

[adzialocha]

I guess this is why send-to-node currently fails, right?

Running `target/debug/send-to-node -k ./key-demo.txt`
▶ Public Key: "2f8e50c2ede6d936ecc3144187ff1c273808185cfbc5ff3d3748d1ff7353fc96"
thread 'main' panicked at 'GraphQL query to fetch `nextArgs` failed:
GQLClient Error: Look at json field for more details
Message: Expected a valid document view id, found: null
', src/main.rs:110:10
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

[sandreae]

Yes! It's fixed in #308 I'll cherry-pick the commit across to main now.

[sandreae]

Should be fixed with this: 89ff11e

[adzialocha]

Amazing, thank you!