# Bizzare error when concatenating deeply indiced strings, "Dereferencing null/undefined value." **URL:** \ **Category:** Help\ **Created:** [January 11, 2023, 6:27pm UTC](https://forum.makecode.com/t/bizzare-error-when-concatenating-deeply-indiced-strings-dereferencing-null-undefined-value/17372 "2023-01-11T18:27:17Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![ADVFRED](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/advfred/32/7481_2.png) [@ADVFRED](https://forum.makecode.com/u/ADVFRED)\ **Post date:** [January 11, 2023, 6:27pm UTC](https://forum.makecode.com/t/bizzare-error-when-concatenating-deeply-indiced-strings-dereferencing-null-undefined-value/17372/1 "2023-01-11T18:27:17Z")
Hello, I’m about at my wits end and would really appreciate some help. The big picture is the player is asked a vocabulary question when the player hits a coin in order to collect the coin. I’m having trouble displaying the question, which is a mash of concatenated text and list indexes.I’m doing the bulk of this code in python, relevant code block below as well as the entire project. I scaled it back to find the breaking point, this segement will be displayed: > question=“HI! \n”+WordList[0][0]+“\n”+WordList[1][0]+“\n”+WordList[2] As will this > question = “Definition of " + WordList[indice][0] + " is:\n”+"1: “+WordList[QuestionIndices[0]][1]+”\n 2: "+WordList[QuestionIndices[1]][1] but not this, adding a third line of blank text to the previous segment causes the error > question = “Definition of " + WordList[indice][0] + " is:\n”+“1: “+WordList[QuestionIndices[0]][1]+”\n 2: “+WordList[QuestionIndices[1]][1]+”\n” I frankly have no idea why this is happening and if anyone has som illumination I would be much obliged. Full relevant code segment: > **[MakeCode Arcade SAT Run - Pastebin.com](https://pastebin.com/fVwL2Z0u)** > > Pastebin.com is the number one paste tool since 2002. Pastebin is a website where you can store text online for a set period of time. Full Program: > **[SAT Run](https://arcade.makecode.com/S96312-19522-31629-13896)** > > Made with ❤️ in Microsoft MakeCode Arcade. ---
**Author:** ![richard](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/richard/32/5417_2.png) [@richard](https://forum.makecode.com/u/richard)\ **Post date:** [January 11, 2023, 6:29pm UTC](https://forum.makecode.com/t/bizzare-error-when-concatenating-deeply-indiced-strings-dereferencing-null-undefined-value/17372/2 "2023-01-11T18:29:20Z")
looks like you have an off by one error in your code: ```python WordIndice = randint(0, len(WordList)) DefinitionIndice = randint(0, len(WordList)) ``` randint is _inclusive_, so both WordIndice and DefinitionIndice have a chance of being set equal to the length of the wordlist, which is an invalid index. if you subtract 1 from the len, then you should be fine! ---
**Author:** ![ADVFRED](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/advfred/32/7481_2.png) [@ADVFRED](https://forum.makecode.com/u/ADVFRED)\ **Post date:** [January 11, 2023, 11:02pm UTC](https://forum.makecode.com/t/bizzare-error-when-concatenating-deeply-indiced-strings-dereferencing-null-undefined-value/17372/3 "2023-01-11T23:02:03Z")
Ohhh, I can’t believe I missed that! 🤦‍♂️ I’ll give that a try once I get home. Thank you so much for the help! ---
**Author:** ![ADVFRED](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/advfred/32/7481_2.png) [@ADVFRED](https://forum.makecode.com/u/ADVFRED)\ **Post date:** [January 12, 2023, 3:59am UTC](https://forum.makecode.com/t/bizzare-error-when-concatenating-deeply-indiced-strings-dereferencing-null-undefined-value/17372/4 "2023-01-12T03:59:09Z")
That did indeed fix it! I really appreciate the help! I haven’t a clue why it was affecting displaying newlines but it thats irrelevant now! 😃