I made all the corrections listed in the answer which has resolved the original error, but I am now recieving the following error:

GroceryList.java:$17$: error: incompatible types: String cannot be converted to int

undoStack.push$($new InsertAtCommand$($listItems$,$ removedItem, removalIndex$))$;

$^$

Note: Some messages have been simplified; recompile with $-$Xdiags:verbose to get full output

$1$ error

I have followed this thread line by line but I am receiving the following error;

Exception in thread "main" java.util.NoSuchElementException: No line found

at java.base$/$java$.$util.Scanner.nextLine$($Scanner$.$java:$1651)$

at LabProgram.main$($LabProgram$.$java:$16)$