Were you able to solve this? I’m having this problem and I have no idea how to fix it.
I am having the same issue. It will pull results for the first character of a search, but then give “Cannot read properties of undefined (reading ‘substring’)” after typing 2 or more characters.
It is worse than ever now and literally happening for any search strings.
It will occasionally allow a whole word to be typed but I think that is more chance than actually anything else.
This issue has been present since Shopify released the code editor and you can see that others are also reporting the same issue. It is making it pretty useless as we are unable to search for anything across the theme.
I don’t know if this helps but I recorded a short gif to show you how temperamental the search is with this error.
Is it always happening with the same theme or is this across any theme? Feel free to drop a theme ID in here and I can poke at it.
@Gray-Shopify this happens in any theme and any Shopify store - it does seem to be worse in some themes compared to others but it’s hard to really gauge that as I will be developing in specific themes more than the others. All I know is that it is not isolated to just one theme.
It also differs across different themes. Like in our live theme I am getting this error searching for “OpenSan” however I can search this in a different theme and not produce the same error.
It may well be something in a theme that is causing the error but I have zero idea what that could be.
Here is the theme ID of the one I am working in if of any use though - 191633850745.
Oddly enough it does seem to be something with that specific theme. I can recreate the issue by searching for open and I can’t replicate that in a different theme. This is a great spot to debug from, thank you!
Okay so long as this helps - I am pretty sure I’ve experienced this search issue in fresh versions of the Dawn theme as well before. It definitely happens a lot in multiple stores/themes, hah.
Let me know if I can do anything or provide anything else that helps.
I think I’ve found it! I’ll let you know when the fix attempt is up.
This should be fixed now 
Let me know if this clears up for you (keep in mind assets for the editor may be cached in your browser).
Alas we had to roll it back due to an issue with the Liquid extension. Fix should go back out this week.
Please give it another go!
So I don’t appear to have experienced the issue this past week so it does look like this may well be fixed. Thanks so much for resolving that. Will update further if it occurs again.
