Why does this Applescript cause "Export Library.scpt: execution error: System Events got an error: Can’t get process "i". (-1728)"? - applescript

Question

ƒIt's caused when run through osascript from terminal using the command line "osascript Export\ Library.scpt /Users/bryandunphy/Development/iTunesLibraryConsolidator testing.xml".
same script as my last (solved) question but posting it's entirety this time.
-- `menu_click`, by Jacob Rus, September 2006
--
-- Accepts a list of form: `{"Finder", "View", "Arrange By", "Date"}`
-- Execute the specified menu item. In this case, assuming the Finder
-- is the active application, arranging the frontmost folder by date.
on menuClick(mList)
local appName, topMenu, r
-- Validate our input
if mList's length < 3 then error "Menu list is not long enough"
-- Set these variables for clarity and brevity later on
set {appName, topMenu} to (items 1 through 2 of mList)
set r to (items 3 through (mList's length) of mList)
-- This overly-long line calls the menu_recurse function with
-- two arguments: r, and a reference to the top-level menu
tell application "System Events" to my menuClickRecurse(r, ((process appName)'s ¬
(menu bar 1)'s (menu bar item topMenu)'s (menu topMenu)))
end menuClick
on menuClickRecurse(mList, parentObject)
local f, r
-- `f` = first item, `r` = rest of items
set f to item 1 of mList
if mList's length > 1 then set r to (items 2 through (mList's length) of mList)
-- either actually click the menu item, or recurse again
tell application "System Events"
if mList's length is 1 then
click parentObject's menu item f
else
my menuClickRecurse(r, (parentObject's (menu item f)'s (menu f)))
end if
end tell
end menuClickRecurse
-- Created by Bryan Dunphy during January of 2017
--
-- select the folder "directory" in Window "WinName" of Application "appName" and then clicks the default button if requested
-- if WinName is "" then it uses the frontmost window (to allow for unnamed windows)
-- REQUIRES "on handleDir" and "on findRoot" to work!
-- ONLY call switchDir
-- "createIt" is a boolean that will create any missing directories if it is set to "true".
-- "selectDefault" is a boolean indicating whether or not to click the window's default button after selecting the specified directory
-- returns "true" or "false" to indicate success.
-- clicks "Cancel" button on failure
-- Always returns "true" if "createIt" is set to "true"
on switchDir(directory, winName, appName, createIt, selectDefault)
local dirs, delim
set delim to AppleScript's text item delimiters
set AppleScript's text item delimiters to "/"
set dirs to every text item of directory
tell application "System Events" to tell process appName to set frontmost to true
my findRoot(appName, winName)
repeat with dir in dirs
if not handleDir(dir, winName, createIt) then
tell application "System Events" to tell process appName to tell button "Cancel" to click
return false
end if
end repeat
if selectDefault then keystroke return
return true
end switchDir
on handleDir(dir, winName, appName, createIt)
local foundIt
foundIt = false
local ndx
if winName is not "" then
repeat with ndx from 1 to (count of window winName's list 1)
if window winName's list 1's item ndx's value is equal to dir then
select window winName's list 1's item ndx
foundIt = true
exit repeat
end if
end repeat
else
repeat with ndx from 1 to (count of front window's list 1)
if front window's list 1's item ndx's value is equal to dir then
select front window's list 1's item ndx
foundIt = true
exit repeat
end if
end repeat
end if
if not foundIt then
if createIt then
if winName is not "" then
tell application "System Events" to tell process appName to tell window winName
tell button "New Folder"
click
repeat until window "New Folder" exists
delay 0.5
end repeat
set value of text field 1 of window "New Folder" to dir
tell button "Create" to click
return my handleDir(dir)
end tell
end tell
else
tell application "System Events" to tell process appName to tell its front window
tell button "New Folder"
click
repeat until window "New Folder" exists
delay 0.5
end repeat
set value of text field 1 of window "New Folder" to dir
tell button "Create" to click
return my handleDir(dir)
end tell
end tell
end if
end if
else
return foundIt
end if
end handleDir
on findRoot(appName, winName)
local rootName
if winName is not "" then
tell application "System Events" to tell process appName to tell window winName
tell pop up button 1
click
repeat until menu 1 exists
delay 0.5
end repeat
local ndx
repeat with ndx from 1 to (count of menu 1)
if the title of menu 1's menu item ndx is "" then
set rootName to the title of menu 1's menu item (ndx - 1)
select (menu 1's menu item (ndx - 1))
exit repeat
end if
end repeat
end tell
end tell
else
tell application "System Events" to tell process appName's front window
tell pop up button 1
click
repeat until menu 1 exists
delay 0.5
end repeat
local ndx
repeat with ndx from 1 to (count of menu 1)
if the title of menu 1's menu item ndx is "" then
set rootName to the title of menu 1's menu item (ndx - 1)
select (menu 1's menu item (ndx - 1))
exit repeat
end if
end repeat
end tell
end tell
end if
return rootName
end findRoot
on run (clp)
if clp's length is not 2 then error "Incorrect Parameters"
local destination, libraryName
set destination to clp's item 1
set libraryName to clp's item 2
menuClick("iTunes", "File", "Library", "Export Library…")
set value of parentObject's text field "Save As:" to (libraryName and ".xml")
tell pop up button 1 of group 1 of window "New iTunes Library" of process iTunes of application "System Events" to click
repeat with ndx from 1 to (count of parentObject's menu 1)
if title of menu item ndx is "" then
select menu item (ndx - 1)
exit repeat
end if
end repeat
my switchDir(destination, "iTunes", "iTunes", true, false)
set the value of text field "Save As:" of window "iTunes" to (libraryName + ".xml")
tell button "Save" of window "iTunes" to click
return (destination and "/" and libraryName and ".xml")
end run

Answer 1

Change:
menuClick("iTunes", "File", "Library", "Export Library…")
to:
menuClick({"iTunes", "File", "Library", "Export Library…"})
AppleScript's error reporting is truly awful (no tracebacks, for starters), and osascript is even worse than Script Editor for debugging. If you run the script in SE, it will at least highlight the line in your script where the error occurred. If that doesn't give you a clue, add log commands to report the script's progress. osascript will write logged messages to stderr. In SE, click the awful 'document' (show/hide log) icon at the bottom of the window, then select 'Messages'. If your time is worth more than $100, get yourself a copy of Script Debugger which also lets you add breakpoints and step through and inspect variables as the script runs.