Invalid Record List Indexer error is issued in the following situations:
'Record List' variable indexer must be an 'Integer'
You are indexing your List using a number that is not an Integer.
Check the data type of your index because the  operator expects an Integer value.
`Only 'Record List' elements can be indexed
you are indexing an element that is not a List`.
Change the element data type because the  operator can only be used with Lists.
Double-click on the error line to take you directly to the element where this situation was detected.