Remove check for inner nullability of component columns (#9009)

### Related
* #8998
* #6819

### What
`pixi run rerun rerun://redap.rerun.io/catalog` failed with `Detected
malformed Chunk: The outer array in chunked component batch must be a
sparse list, got List(Field { name: "item", data_type: Utf8, nullable:
false, dict_id: 0, dict_is_ordered: false, metadata: {} })`.

The cause was a check in the `Chunk::sanity_check` requiring _inner
mutability_, i.e. allowing a single component to be null in a list. The
intention of the check was to check for _outer_ nullability, i.e. that
any cell in the column can be `null` (or a dense list).

In other words, we want to support `Vec<Option<Vec<T>>`, but NOT require
`Vec<Option<Vec<Option<T>>>`.

Why did this trigger now? Because we now allow sending component columns
as "mono components", i.e. as `Vec<T>` and that is then automatically
changed to `Vec<Vec<T>>`, but wether or not it has interior nullability
depends on if the source data had it.

crates/store/re_chunk/src/chunk.rs

@@ -1521,24 +1521,19 @@ impl Chunk {
             component_name.sanity_check();
             for (component_desc, list_array) in per_desc {
                 component_desc.component_name.sanity_check();
-                if !matches!(list_array.data_type(), arrow::datatypes::DataType::List(_)) {
+                // Ensure that each cell is a list (we don't support mono-components yet).
+                if let arrow::datatypes::DataType::List(_field) = list_array.data_type() {
+                    // We don't check `field.is_nullable()` here because we support both.
+                    // TODO(#6819): Remove support for inner nullability.
+                } else {
                     return Err(ChunkError::Malformed {
                         reason: format!(
-                            "The outer array in a chunked component batch must be a sparse list, got {:?}",
+                            "The inner array in a chunked component batch must be a list, got {:?}",
                             list_array.data_type(),
                         ),
                     });
                 }
-                if let arrow::datatypes::DataType::List(field) = list_array.data_type() {
-                    if !field.is_nullable() {
-                        return Err(ChunkError::Malformed {
-                            reason: format!(
-                                "The outer array in chunked component batch must be a sparse list, got {:?}",
-                                list_array.data_type(),
-                            ),
-                        });
-                    }
-                }
+
                 if list_array.len() != row_ids.len() {
                     return Err(ChunkError::Malformed {
                         reason: format!(

crates/store/re_grpc_client/src/redap/mod.rs

@@ -71,15 +71,15 @@ pub fn stream_from_redap(
                 recording_id,
             } => {
                 if let Err(err) = stream_recording_async(tx, origin, recording_id, on_msg).await {
-                    re_log::warn!(
+                    re_log::error!(
                         "Error while streaming {url}: {}",
                         re_error::format_ref(&err)
                     );
                 }
             }
             RedapAddress::Catalog { origin } => {
                 if let Err(err) = stream_catalog_async(tx, origin, on_msg).await {
-                    re_log::warn!(
+                    re_log::error!(
                         "Error while streaming {url}: {}",
                         re_error::format_ref(&err)
                     );