UPDATE subquery panics

[xxchan]

Describe the bug

No response

Error message/log

No response

To Reproduce

dev=> create table t1(x int, y int);
CREATE_TABLE
dev=> create table t2(x int, y int);
CREATE_TABLE
dev=> update t1 set x = (select x from  (select x,y from t2) as subquery where subquery.y=t1.y)
dev-> ;
ERROR:  Panicked when handling the request: internal error: entered unreachable code: Subquery Subquery { kind: Scalar, query: BoundQuery { body: Select(BoundSelect { distinct: All, select_items: [$0], aliases: [Some("x")], from: Some(Subquery(BoundSubquery { query: BoundQuery { body: Select(BoundSelect { distinct: All, select_items: [$0, $1], aliases: [Some("x"), Some("y")], from: Some(BaseTable(BoundBaseTable { table_id: TableId { table_id: 10 }, table_catalog: TableCatalog { id: TableId { table_id: 10 }, associated_source_id: None, name: "t2", dependent_relations: [], columns: [ColumnCatalog { column_desc: ColumnDesc { data_type: Int32, column_id: #1, name: "x", field_descs: [], type_name: "", generated_or_default_column: None, description: None, additional_column: AdditionalColumn { column_type: None }, version: Pr13707 }, is_hidden: false }, ColumnCatalog { column_desc: ColumnDesc { data_type: Int32, column_id: #2, name: "y", field_descs: [], type_name: "", generated_or_default_column: None, description: None, additional_column: AdditionalColumn { column_type: None }, version: Pr13707 }, is_hidden: false }, ColumnCatalog { column_desc: ColumnDesc { data_type: Serial, column_id: #0, name: "_row_id", field_descs: [], type_name: "", generated_or_default_column: None, description: None, additional_column: AdditionalColumn { column_type: None }, version: Pr13707 }, is_hidden: true }], pk: [$2 ASC], stream_key: [2], table_type: Table, distribution_key: [2], append_only: false, cardinality: Cardinality { lo: 0, hi: Unlimited }, owner: 1, retention_seconds: None, fragment_id: 6, dml_fragment_id: Some(7), vnode_col_index: None, row_id_index: Some(2), value_indices: [0, 1, 2], definition: "CREATE TABLE t2 (x INT, y INT)", conflict_behavior: Overwrite, version_column_index: None, read_prefix_len_hint: 1, version: Some(TableVersion { version_id: 0, next_column_id: #3 }), watermark_columns: FixedBitSet { data: [0], length: 3 }, dist_key_in_pk: [], created_at_epoch: Some(Epoch(7458118959104000)), initialized_at_epoch: Some(Epoch(7458118959104000)), cleaned_by_watermark: false, create_type: Foreground, stream_job_status: Created, description: None, incoming_sinks: [], created_at_cluster_version: Some("PostgreSQL 13.14.0-RisingWave-2.2.0-alpha (unknown)"), initialized_at_cluster_version: Some("PostgreSQL 13.14.0-RisingWave-2.2.0-alpha (unknown)"), cdc_table_id: None, vnode_count: Set(256) }, table_indexes: [], as_of: None })), where_clause: None, group_by: GroupKey([]), having: None, schema: Schema { fields: [x:Int32, y:Int32] } }), order: [], limit: None, offset: None, with_ties: false, extra_order_exprs: [] }, lateral: false })), where_clause: Some(($1 = CorrelatedInputRef { index: 1, correlated_id: 0 })), group_by: GroupKey([]), having: None, schema: Schema { fields: [x:Int32] } }), order: [], limit: None, offset: None, with_ties: false, extra_order_exprs: [] } } has not been unnested
This is a bug. We would appreciate a bug report at:
  https://github.com/risingwavelabs/risingwave/issues/new?labels=type%2Fbug&template=bug_report.yml

Expected behavior

No response

How did you deploy RisingWave?

No response

The version of RisingWave

No response

Additional context

found by customer https://risingwave-labs.slack.com/archives/C07G5HHDU31/p1731033287039829

[chenzl25]

Risingwave doesn't support subquery in the update set lists. Maybe we should detect it and throw an error instead of panic.

[BugenZhao]

Can be traced back to #2672