Check if a FieldHandle exists in Module without throwing 'Invalid field handle' exceptions
Without modifying your code too much, you could simply add an exception handler with a try/catch block.
Another method would be to retrieve the field handles for the entry type's field layout, and check for a match:
Getting the $entryType as necessary,
$etFieldHandles = [];
$fields = $entryType-&gt;getFieldLayout()-&gt;getFields();
foreach ($fields as $field) {
    $etFieldHandles[] = $field-&gt;handle;
}

if (in_array('yourfieldhandle', $etFieldHandles) ) {
    // the field exists in this entry type's layout.
}