If you use acf_add_local_field_group() before acf/init and then immediately try to get a field in that group then you are likely trying to get the field before acf/init unless you are adding the field group on the acf/init hook. The documentation on this says you can do one acf/init OR in functions.php, but the documentation could be wrong.
Here is the code before the error is shown
if ( did_action( 'init' ) ) {
return;
}
/// outputs error here
if you call get_field() before init has fired you will get the error.
