[Bug] External volume name set as None when omitted in Iceberg tables

[dlouseiro]

Is this a new bug in dbt-snowflake?

• I believe this is a new bug in dbt-snowflake
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

When a external_volume is omitted in the definition of an Iceberg table, the create table statement uses external_volume='None'.

As Snowflake allows for the creation of Iceberg tables without specifying an external volume (picking up the external volume attached to the schema or database) and the field is defined as optional, this does not seem like an expected behaviour.

Expected Behavior

external_volume specification is omitted from create table statement if the volume is not defined in the model's configuration.

Steps To Reproduce

1. Define an Iceberg table model, omitting the external_volume
2. Run code
3. Check target/run code for a create table statement with external_volume='None'

Relevant log output

Environment

- OS: macOS 15.2
- Python: 3.11.11
- dbt-core: 1.9.1
- dbt-snowflake: 1.9.0

Additional Context

No response