Not enough data to fill buffer

Ver v0.8.0
Blocktime 6_000

called `Result::unwrap()` on an `Err` value: Input("Error { cause: Some(Error { cause: None, desc: \"Not enough data to fill buffer\" }), desc: \"Could not decode `ExtrinsicInclusionMode`, failed to read variant byte\" }")

Blocktime 12_000

called `Result::unwrap()` on an `Err` value: Input("failed to execute 'Core_initialize_block': Execution aborted due to trap: wasm trap: wasm `unreachable` instruction executed\nWASM backtrace:\nerror while executing at wasm backtrace:\n    0: 0x5ea17c - <unknown>!rust_begin_unwind\n    1: 0xc4e1 - <unknown>!core::panicking::panic_fmt::h6522c6a1bf300b70\n    2: 0x176590 - <unknown>!<pallet_aura::pallet::Pallet<T> as frame_support::traits::hooks::OnInitialize<<<<T as frame_system::pallet::Config>::Block as sp_runtime::traits::HeaderProvider>::HeaderT as sp_runtime::traits::Header>::Number>>::on_initialize::h352ecb1006b3125e\n    3: 0x33b735 - <unknown>!<(TupleElement0,TupleElement1,TupleElement2,TupleElement3,TupleElement4,TupleElement5,TupleElement6,TupleElement7,TupleElement8,TupleElement9,TupleElement10,TupleElement11,TupleElement12,TupleElement13,TupleElement14,TupleElement15,TupleElement16,TupleElement17,TupleElement18,TupleElement19,TupleElement20,TupleElement21,TupleElement22,TupleElement23,TupleElement24,TupleElement25,TupleElement26,TupleElement27,TupleElement28,TupleElement29,TupleElement30,TupleElement31,TupleElement32,TupleElement33,TupleElement34) as frame_support::traits::hooks::OnInitialize<BlockNumber>>::on_initialize::hac9f1198775d081c\n    4: 0x61957 - <unknown>!frame_executive::Executive<System,Block,Context,UnsignedValidator,AllPalletsWithSystem,COnRuntimeUpgrade>::initialize_block::hc2ef4267e6ec6443\n    5: 0x4f34ea - <unknown>!Core_initialize_block")

Reproduce the v0.8.0 case at blocktimes 6_000 and 12_000, then trace the reported ExtrinsicInclusionMode decode failure and Core_initialize_block/pallet_aura backtrace. Since no target behavior or test is named, first establish the failing component and a regression check; done should mean the failure is resolved or reported with a clear, reproducible diagnosis.