Hello Morgan Baggs,
I am not from support, but I already know the problem.
I have already provided a patch for this.
https://github.com/JoomShaper/Helix3/pull/112/commits/079bb8f33d3c39b1c39ebc1d0bdb5f32da3e1a72
If you make these adjustments in your "plugins/system/helix3/core/helix3.php" file, the error should be gone.
To be on the safe side that it is indeed the same problem, please trigger the error once with debug mode enabled.
You should then know the exact files that triggered the error and where exactly.
For this Joomla should generate a display with the text "Call Stack" in debug mode.
You activate the debug mode via: System -> Configuration -> System -> Debug Settings -> Debug System
If it is not fixed by this patch, please let me know the message generated by Joomla with enable debug mode.
So I can reproduce the problem and provide a solution for you.
With kind regards