Error is thrown when using DateRangeValidator

[bbtechd]

Hello,

when i try using the "DateRangeValidator" for the "Date Picker" element, i get the following error, if the user inserts a date, which is not in the range of the Validator.

An exception was thrown while Neos tried to render your page
Provided formatType, "datetime", is not one of allowed values.

src/Data/Temporary/Development/Cache/Code/Flow_Object_Classes/Neos_Flow_I18n_Formatter_DatetimeFormatter.php: Provided formatType, "datetime", is not one of allowed values.

The funny part is, that the Neos/Flow/I18n/Formatter/DatetimeFormatter Class expect the formType "dateTime" and not "datetime" but im not sure, why the format string is given in lowercase.

I have installed the following Versions
neos/neos 8.3.12
neos/form-builder 2.3.4

To reproduce the error

1. Add the element "Form" in the content tree
   

2. Add "Date picker" under "Elements" in the form
   

3. Under "Validators", select "DateTime range validator"
   

4. In the inspector of "DateTime range validator", select the earliest and latest date (in the example 14.05 to 18.05)
   

5. Select a date in the form that is outside the selected period (in the example, the error is thrown for everything up to 13.05 and everything from 18.05)

6. The error will be thrown as shown in the picture
   

Thanks in advance for your help