How to decode URL component using M Language?

I have a column with links in it, I need to decode it. The links are encoded, in %s as shown below

For example:  https%3A%2F%2Fwww.rnd.de%2Fpanorama%2Fzwei-flugzeuge-stossen-im-munsterland-zusammen-beide-piloten-tot-YDHGMRPATRCUBC6SCDD27TSQRU.html

should be decoded to 
https://www.rnd.de/panorama/zwei-flugzeuge-stossen-im-munsterland-zusammen-beide-piloten-tot-YDHGMRPATRCUBC6SCDD27TSQRU.html 

I found a solution here: 

https://stackoverflow.com/questions/36242695/how-to-decodeuricomponent-ex-2f3f263d

But I am very new to M code so I don't know where I'm going wrong. But it gives me this error

This is the code I have written

let
InputData = Excel.Workbook(File.Contents("C:\Users\Fatima\Downloads\Microsoft.SkypeApp_kzf8qxf38zg5c!App\All\encoded-URLs.xlsx"), null, true),
Uri.UnescapeDataString = (data as text) as text => let
ToList = Text.ToList(data),
Accumulate = List.Accumulate(ToList, [ Bytes = {} ], (state, current) =>
let
HexString = state[HexString]?,
NextHexString = HexString & current,
NextState = if HexString <> null
then if Text.Length(NextHexString) = 2
then [ Bytes = state[Bytes] & Binary.ToList(Binary.FromText(NextHexString, BinaryEncoding.Hex)) ]
else [ HexString = NextHexString, Bytes = state[Bytes] ]
else if current = "%"
then [ HexString = "", Bytes = state[Bytes] ]
else [ Bytes = state[Bytes] & { Character.ToNumber(current) } ]
in
NextState),
FromBinary = Text.FromBinary(Binary.FromList(Accumulate[Bytes]))
in
FromBinary,

AddEscaped = Table.AddColumn(InputData, "Escaped", each Uri.EscapeDataString([Column1])),

AddUnescaped = Table.AddColumn(AddEscaped, "Custom", each Uri.UnescapeDataString([Escaped]))
in
AddUnescaped

Can anyone tell me where I'm going wrong?