Assigning multiple sub types in Fluid throws error

[Chris Müller]

When assigning multiple sub types (three or more) to a type with a Fluid view helper, an error occurs:

Call to a member function toArray() on array

Example:

<schema:type.organization
    name="Acme Ltd."
    url="https://www.example.org/"
    logo="https://www.example.org/logo.png"
>
    <schema:type.contactPoint
        -as="contactPoint"
        telephone="[phone]"
        contactType="sales"
        areaServed="DE"
    />
    <schema:type.contactPoint
        -as="contactPoint"
        telephone="[phone]"
        contactType="sales"
        areaServed="PL"
    />
    <schema:type.contactPoint
        -as="contactPoint"
        telephone="[phone]"
        contactType="sales"
        areaServed="TR"
    />
</schema:type.organization>