fix: address review nits on the duckdb bump

Name the unsupported DuckDB type rather than dumping the value, which may be
arbitrarily large or hold data that does not belong in an error message, and
say which column it came from.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

backend/ee-repo-ref.txt

@@ -1 +1 @@
-ec55b3c383631f7a0eefa7266a5c474b518b6aea
+a3ab9e057452a6508e7402c96a866dc1e78aaf44

backend/windmill-duckdb-ffi-internal/src/lib.rs

@@ -621,7 +621,8 @@ fn row_to_value(
     for (i, key) in column_names.iter().enumerate() {
         let value: duckdb::types::Value = row.get(i).map_err(|e| e.to_string())?;
         let type_alias = &type_aliases[i];
-        let json_value = duckdb_value_to_json_value(value, type_alias)?;
+        let json_value = duckdb_value_to_json_value(value, type_alias)
+            .map_err(|e| format!("column \"{key}\": {e}"))?;
         obj.insert(key.clone(), json_value);
     }
     serde_json::value::to_raw_value(&obj).map_err(|e| e.to_string())
@@ -715,12 +716,15 @@ fn duckdb_value_to_json_value(
         ),
         duckdb::types::Value::Union(value) => serde_json::Value::String(format!("{:?}", *value)),
         // `Value` is `#[non_exhaustive]`: a newer engine can hand back a variant this
-        // build has never seen. Name it instead of emitting a plausible-looking
-        // rendering that silently misrepresents the column.
+        // build has never seen. Name its type instead of emitting a plausible-looking
+        // rendering that silently misrepresents the column. The type, never the value:
+        // a row that reaches here is already unprintable, and it may be arbitrarily
+        // large or hold data that does not belong in a job's error message.
         other => {
             return Err(format!(
-                "Unsupported DuckDB value for this build: {:?}",
-                other
+                "DuckDB type {:?} is not supported by this worker's engine bindings; \
+                 cast the column to a supported type (e.g. VARCHAR) to return it",
+                other.data_type()
             ))
         }
     };