[TYPO3-english] tx_form error on submit

[Glenn S]

With TYPO3 7.6 and the built-in extension tx_form, I'm trying to create an email form. When I submit it, I get an error.

I've done the following steps:

Added 'Default TS (form)' to the includes of my root page.

Configured email and checked that I can send myself a test email from the install tool.

Added a content element of type Form to a page.

The 'Form' tab of the Form content elements looks like this: https://pastebin.com/2pNydDsN (I've written the simplest example I could to make this easier to debug).

When I view the form in the page and click submit, I get 3 errors from the getView method of TYPO3\CMS\Form\PostProcess\MailPostProcessor, the last one of which is fatal. All of them are caused by the $typoScript array not having the key 'view'. This $typoScript array is gotten by asking the ConfigurationManager for Framework Configuration.

The error message I actually get back is:
"Argument 1 passed to TYPO3\CMS\Fluid\View\StandaloneView::setLayoutRootPaths() must be of the type array, null given"

Here is the breaking method: 
https://github.com/TYPO3/TYPO3.CMS/blob/TYPO3_7-6/typo3/sysext/form/Classes/PostProcess/MailPostProcessor.php#L485

I'm guessing that I need to add some configuration, but I can't find out where because I don't know what 'Framework Configuration' means.

Help much appreciated.

Thanks,
Glenn