yarn run -TB wireit gets a loop lock if script is missing

Inside `some-project/packages/some-package/package.json`:

```js
{
"scripts": {
"some-command": "yarn run -TB wireit"
},
"wireit": {
//... but with no entry for "some-command"
}
}
```

## Expected

Error saying `some-command` entry could not be found in `wireit` config. (This issue originally arose because I put the command config one level too high in the JSON tree.)

## Actual
```
cd some-project/packages/some-package
yarn run some-command
🏃 [some-command] Running command "yarn run -TB wireit"
💤 [some-command] Waiting for another process which is already running this script.
```