bug(frontend): unnest cause panic

[KeXiangWang]

Describe the bug

Still part of subquery. Not sure whether retated to #14423

Error message/log

part of the error message

thread 'rw-main' panicked at src/frontend/src/expr/subquery.rs:101:9:
internal error: entered unreachable code: Subquery Subquery { kind: Array, query: BoundQuery { body: Query(BoundQuery { body: Select(BoundSelect { distinct: All, select_items: [GenerateSeries(0:Int32, -2:Int32, 1:Int32)], aliases: [Some("generate_series_1")], from: None, where_clause: None, group_by: GroupKey([]), having: None, schema: Schema { fields: [generate_series_1:Int32] } }), order: [], limit: None, offset: None, with_ties: false, extra_order_exprs: [] }), order: [], limit: None, offset: None, with_ties: false, extra_order_exprs: [] } } has not been unnested
stack backtrace:
   0: rust_begin_unwind
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/std/src/panicking.rs:645:5
   1: core::panicking::panic_fmt
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/core/src/panicking.rs:72:14
   2: <risingwave_frontend::expr::subquery::Subquery as risingwave_frontend::expr::Expr>::to_expr_proto
             at ./src/frontend/src/expr/subquery.rs:101:9
   3: <risingwave_frontend::expr::ExprImpl as risingwave_frontend::expr::Expr>::to_expr_proto
             at ./src/frontend/src/expr/mod.rs:108:45
   4: core::ops::function::FnMut::call_mut
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/core/src/ops/function.rs:166:5
   5: core::iter::adapters::map::map_fold::{{closure}}
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/core/src/iter/adapters/map.rs:85:28
   6: <core::slice::iter::Iter<T> as core::iter::traits::iterator::Iterator>::fold
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/core/src/slice/iter/macros.rs:232:27
   7: <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::fold
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/core/src/iter/adapters/map.rs:125:9
   8: core::iter::traits::iterator::Iterator::for_each
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/core/src/iter/traits/iterator.rs:858:9
   9: alloc::vec::Vec<T,A>::extend_trusted
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/alloc/src/vec/mod.rs:2923:17
  10: <alloc::vec::Vec<T,A> as alloc::vec::spec_extend::SpecExtend<T,I>>::spec_extend
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/alloc/src/vec/spec_extend.rs:26:9
  11: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter_nested::SpecFromIterNested<T,I>>::from_iter
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/alloc/src/vec/spec_from_iter_nested.rs:62:9
  12: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/alloc/src/vec/spec_from_iter.rs:33:9
  13: <alloc::vec::Vec<T> as core::iter::traits::collect::FromIterator<T>>::from_iter
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/alloc/src/vec/mod.rs:2791:9
  14: core::iter::traits::iterator::Iterator::collect
             at /rustc/e4c626dd9a17a23270bf8e7158e59cf2b9c04840/library/core/src/iter/traits/iterator.rs:2054:9
  15: <risingwave_frontend::expr::function_call::FunctionCall as risingwave_frontend::expr::Expr>::to_expr_proto
             at ./src/frontend/src/expr/function_call.rs:300:27
  16: <risingwave_frontend::expr::ExprImpl as risingwave_frontend::expr::Expr>::to_expr_proto
             at ./src/frontend/src/expr/mod.rs:108:45

To Reproduce

SELECT anon_1.f1 AS "IntegerRange(0, -2, 1)" 
FROM unnest(CASE WHEN (nullif(1, 0) IS NOT NULL AND sign(1) = sign( -2 - 0)) THEN array_remove(array((SELECT generate_series(0,  -2, 1) AS generate_series_1)),  -2) ELSE CAST(ARRAY[] AS SMALLINT[]) END) AS anon_1(f1);

Expected behavior

At least not panic

How did you deploy RisingWave?

No response

The version of RisingWave

657b8ab (newest main)

Additional context

No response

[chenzl25]

The error should be reported as Not supported: use subuqery in a table function. We can't support subquery in tablefunction.