I have a form that uses a field of type DatePicker. The field seems to work all right, but generates errors in the log. There are three fields on my form and I get the errors in triplets (not sure if same three):
[15-Apr-2019 17:06:01 America/Winnipeg] PHP Warning: count(): Parameter must be an array or an object that implements Countable in /<blanking for security>/extensions/PageForms/includes/forminputs/PF_DatePickerInput.php on line 391
[15-Apr-2019 17:06:01 America/Winnipeg] PHP Warning: count(): Parameter must be an array or an object that implements Countable in /<blanking for security>/extensions/PageForms/includes/forminputs/PF_DatePickerInput.php on line 410
[15-Apr-2019 17:06:01 America/Winnipeg] PHP Warning: count(): Parameter must be an array or an object that implements Countable in /<blanking for security>/extensions/PageForms/includes/forminputs/PF_DatePickerInput.php on line 415

Versions:
MediaWiki 1.32.0
PHP 7.2.11 (cgi-fcgi)
MySQL 5.7.25-log
SMW 3.0.2
PF 4.5