Michael Simpson on "[Plugin: Contact Form DB] filter for exact name but case insensitive"

Stumbled upon something called strtolower. Works -- except when corresponding input field is left empty retus big error message "Waing: strtolower() expects parameter 1 to be string, array given in ..." No harm to functionality, just ugly and scary to users. Is there a way to avoid/suppress that message -- or another method to do an exact match that is not case sensitive?

'<form action="" method="POST">Zip Code: <input type="text" name="zip5" /> Last Name: <input type="text" name="last-name" /> First Name: <input type="text" name="first-m" /> <input type="hidden" name="x" value="1"/> <input type="submit" /> </form>'

'[cfdb-datatable form="my-form2" show="date,last-name,first-m,city,state,zip5" filter="zip5=$_POST(zip5)&&strtolower(last-name)=strtolower($_POST(last-name))&&first-m~~/$_POST(first-m).*/i&&intval(1)=$_POST(x)" ]'

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