Rejecting react redux form with async/throw instead of promise

I am using react redux form to send form data to server. The form will correctly show failed if I return a promise that fails but not if I throw or use async/await with throw. I still have to return a rejected promise. Not sure what I am missing here or if that's the way of things.

Works:

export const myRequest = (data) => {
   return new Promise((resolve, reject) => {
    reject('Login failed!')
   })
}

Does not (as well as the async/await variants):

export const myRequest = (data) => {
   throw new Error('Login failed')
}

What I have to do:

export const myRequest = (data) => {
  try {
    ...
  } catch (err) {
     return new Promise((resolve, reject) => {
       reject(...)
   })
  }  
}

Here's some async code I am working with. I have to wrap the error message in a promise in order for the form to get the message, I am not sure why it doesn't get the message the same way when I throw.

const myRequest = async ( data) => {
  try {
    let response = await fetch(url, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(data)
    })

    if (!response.ok) {
      throw new Error(response.statusText)
    }
    return await response.json()
  } catch (err) {
    // Not working - no error message makes it - though it gets that it's an error
    throw new Error(err) // or new Error(err.message) or new Error('foo')

    // Works
    // return new Promise((resolve, reject) => {
    //   reject(err.message)
    // })
  }
}

My React Redux Form:

import myRequest from '...'

handleSubmit (values) {
  const { dispatch } = this.props
  dispatch(actions.submit('subscribe', myRequest(values)))
}

render () {
   const { valid, pending, submitted, submitFailed } = this.props.form
  return (
    <Form model='subscribe' onSubmit={(values) => this.handleSubmit(values)}>
    { !valid && submitFailed ? <Alert>          
      <Errors
        model='subscribe' // Form name as found in reducer
      /> : null
    }
    </Form>
  }
}