wasm-reduce crash on WasmValidator

[kripken]

void Reducer::reduceFunctions(): Assertion `WasmValidator().validate( *module, WasmValidator::Globally | WasmValidator::Quiet)' failed.

I can try to get a testcase for this @tlively but maybe it is obvious enough from the location? (getting a testcase will not be fun..)

[kripken]

After removing the Quiet, this is the validation error:

|    try to remove functions
|     try partition 1 / 1 (size 0 / 1211)
[wasm-validator error in function 1357] block with value and last element with value must match types, on 
(block (result nullref)
 (block (result (ref null $struct.0))
  (ref.null none)
 )
)
[wasm-validator error in function 1362] block with value and last element with value must match types, on 
(block (result nullref)
 (block (result (ref null $struct.0))
  (ref.null none)
 )
)
[wasm-validator error in function 1365] block with value and last element with value must match types, on 
(block (result nullref)
 (block (result (ref null $struct.0))
  (ref.null none)
 )
)

[tlively]

Taking a look.

[kripken]

Thanks!