Hi Gumbanomicon,
sorry for coming back at you so late. I've checked your tree, and boy, that thing is massive. Its awesome to see people use this tool to make awesome stuff. Thank you!
Regarding your issue. The parent for Moderate Elixer is Minor Elixer. In the Techtree.json, there are two spaces between Minor and Elixer. That leads to the error. Check line 4221 of the pastebin you posted. Removing one space fixes the issue.
Best regards,
Felski