The following wat program works fine in wat2wasm without function references enabled:
```
(module
  (func $example (export "example") (result funcref)
    ref.func $example))
```

However, enabling the "function references" feature causes the following error:
```
Error: validate failed:
test.wast:3:5: error: type mismatch in implicit return, expected [funcref] but got [(ref 0)]
    ref.func $example))
    ^^^^^^^^
```

It looks like `ref 0` is not marked as a subtype of `funcref`.

Tested with the online demo: https://webassembly.github.io/wabt/demo/wat2wasm/


Incorrect type for ref.func when function references are enabled
This is a GitHub Issue
repo:wabt
owner:WebAssembly
Title : Incorrect type for ref.func when function references are enabled
Issue date:

--- start body ---
The following wat program works fine in wat2wasm without function references enabled:
```
(module
  (func $example (export "example") (result funcref)
    ref.func $example))
```

However, enabling the "function references" feature causes the following error:
```
Error: validate failed:
test.wast:3:5: error: type mismatch in implicit return, expected [funcref] but got [(ref 0)]
    ref.func $example))
    ^^^^^^^^
```

It looks like `ref 0` is not marked as a subtype of `funcref`.

Tested with the online demo: https://webassembly.github.io/wabt/demo/wat2wasm/


--- end body ---
