WSCRIPT error: subscript out of range - vbscript

Question

I have a VBScript which tries to merge data from two CSV files based upon common field. When I am running my script, then I get an error on Line 5 char 1:
Subscript out of range.
The two files which I am trying to merge based upon the value of a common field between the two are in the same folder where script is also placed.
My code is :
'Instatiate FSO.
Set objFSO = CreateObject("Scripting.FileSystemObject")
'Open the CSV file for reading. The file is in the same folder as the script and named csv_sample.csv.
Wscript.Echo "Path " & objFSO.GetParentFolderName(WScript.ScriptFullName)
'Open the store locations file first
Set brandCSV = objFSO.OpenTextFile(objFSO.GetParentFolderName(WScript.ScriptFullName) & "\" & "SizeGuideLookup_test.csv",1,False)
'Set header status to account for the first line as the column headers.
IsHeader = True
'Initialize the var for the output string.
OutRecord = ""
'Read each line of the file.
Wscript.Echo "Starting Brand File loop"
Do Until brandCSV.AtEndOfStream
brandLine = brandCSV.ReadLine
If IsHeader Then
OutTxt = "PIM Size Type,PIM Identifier,Structure Group,PIM Size Groupd Value Lookup,Size Group To Upload" & vbCrLf
IsHeader = False
Else
'parse brandrecord and get brand id
brandLineArray=Split(brandLine,";")
brandBrandId = brandLineArray(0)
' loop through Store Location file and get matching data
foundLocation=false
Set storeLocCSV = objFSO.OpenTextFile(objFSO.GetParentFolderName(WScript.ScriptFullName) & "\" & "SizeGuideMapping.csv",1,False)
Do Until storeLocCSV.AtEndOfStream
outLine=""
storeLine=storeLocCSV.ReadLine
storeLineArray=Split(storeLine,";")
storeBrandId = storeLineArray(0)
'if the brand IDs match, append the brand data to the end of the store data.
If brandBrandId = storeBrandId Then
' match found - ouptut data (specific fields from store Line + brand line)
outLine = outLine & brandLineArray(0)
outLine = outLine & "," & brandLineArray(1)
outLine = outLine & "," & brandLineArray(2)
outLine = outLine & "," & storeLineArray(1)
outLine = outLine & "," & storeLineArray(1)
foundLocation=true
'append created line to end of output text data
OutTxt = OutTxt & outLine & vbCrLf
End If
Loop
'Close the store location file.
storeLocCSV.close
'if we havent found the data, add empty fields to end of line
if foundLocation=false Then
' no locations for this brand - create brand-only record
outLine = brandLineArray(0) & ",,,"
outLine = outLine & "," & brandLineArray(1)
outLine = outLine & "," & brandLineArray(2)
outLine = outLine & "," & storeLineArray(1)
outLine = outLine & "," & storeLineArray(1)
'append created line to end of output text data
OutTxt = OutTxt & outLine & vbCrLf
end if
End If
Loop
'Close the brand file.
brandCSV.Close
'Open the output file for writing.
Set objOutCSV = objFSO.CreateTextFile(objFSO.GetParentFolderName(WScript.ScriptFullName) & "\" & "brandfile.csv",True)
'Write the var OutTxt to the file overwriting existing contents.
objOutCSV.Write OutTxt
'Close the file.
objOutCSV.Close
Set objFSO = Nothing

Answer 1

The line the error occurs on doesn't tally with the source you have provided (guessing that's not all of it) but it's likely the
WScript.Arguments(0)
causing the Subscript out of range error as the script is expecting an argument (WshUnnamed or WshNamed objects) being passed but there doesn't appear to be one at index 0 in the WshArguments collection object.
If the argument is indeed a file path, then you want to be calling it with either wscript.exe or cscript.exe something like this (at a Command Prompt);
cscript.exe /nologo "yourscript.vbs" "C:\some\file\path"
Then when
WScript.Echo "Path " & WScript.Arguments(0)
is called you should get (based off this example)
C:\some\file\path
Useful Links
Arguments Property (WScript Object)
WshArguments Object

Answer 2

If i am right, you want to get the folder path of the executing script.
For this purpose, you don't want to use WScript.Arguments(0) but FSO.GetParentFolderName(WScript.ScriptFullName).