Error message during recording

[mariri]

Hi guys !

I have some random error messages that appear during data recording in NuBuilder : "Warning: count(): Parameter must be an array or an object that implements Countable in [...]\nudata.php on line 40" :

for($i = 0 ; $i < count($sf->rows) ; $i++){
}

Sometimes it works well, I can record data without any problem. Sometimes it doesn't without any explanation.
I noticed this will usually occur when I try to record a data registered in a lookup field.

My config (just in case) :
PHP 7.3.5
I use WAMP
Apache 2.4.39
PHPMyAdmin 4.8.5

Thanks in advance for ur help !