Another remark: It seems this behavior is consistent: if I comment out the last equation before the one I told you before, again the next formula works fine, 

El dom, 25 feb 2024 a las 15:38, Andres Conrado Montoya (<andresconrado@gmail.com>) escribió:
A remark: A few lines above the error triggering point, I found a single digit presented as math: \math{5}. Removing this and leaving the 5 in text mode removes the error below it. 
Could it be a bug in the distribution?

El dom, 25 feb 2024 a las 15:24, Andres Conrado Montoya (<andresconrado@gmail.com>) escribió:
I keep bumping into this error, I have no idea what may be causing it, in a statistics book with lots of math: 

registered function call [250]: ...mtx/tex/texmf-context/tex/context/base/mkxl/lxml-mms.lmt:749: attempt to index a nil value (local 'a2')

I have checked everything. I have tried commenting out many things and the weird part is that it fails in a simple math expression: \math{E_{i}j}. Even a simple $y$ or \math{a+b} will trigger the error. However, this same file Im working on has many formulas before that, those work fine. I changed all the $...$ to \math{...} just in case, but with no success. 

Already tried remaking, regenerating, updating the distribution.

Do you have any ideas to work this out? I don't know how to provide a MWE for this because it's a very big project (statistics book).  

I have tried 2 versions, the system-wide one, just upgraded: 
mtx-context     | ConTeXt Process Management 1.06
mtx-context     | current version: 2024.02.22 18:31

And a less recent version, attached to the project:
mtx-context     | ConTeXt Process Management 1.05
mtx-context     | current version: 2024.02.14 13:38


Any help will be much appreciated. 

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Los fines no justifican los medios, porque la medida verdadera de nuestro carácter está dada por los medios que estamos dispuestos a utilizar, no por los fines que proclamamos.
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“You develop an instant global consciousness, a people orientation, an intense dissatisfaction with the state of the world, and a compulsion to do something about it. From out there on the moon, international politics look so petty. You want to grab a politician by the scruff of the neck and drag him a quarter of a million miles out and say, ‘Look at that, you son of a bitch.’” — Apollo 14 astronaut Edgar Mitchell



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Los fines no justifican los medios, porque la medida verdadera de nuestro carácter está dada por los medios que estamos dispuestos a utilizar, no por los fines que proclamamos.
----------------------------------------

“You develop an instant global consciousness, a people orientation, an intense dissatisfaction with the state of the world, and a compulsion to do something about it. From out there on the moon, international politics look so petty. You want to grab a politician by the scruff of the neck and drag him a quarter of a million miles out and say, ‘Look at that, you son of a bitch.’” — Apollo 14 astronaut Edgar Mitchell



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Andrés Conrado Montoya
Andi Kú
andresconrado@gmail.com
http://sesentaycuatro.com
http://messier87.com
http://chiquitico.org
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Los fines no justifican los medios, porque la medida verdadera de nuestro carácter está dada por los medios que estamos dispuestos a utilizar, no por los fines que proclamamos.
----------------------------------------

“You develop an instant global consciousness, a people orientation, an intense dissatisfaction with the state of the world, and a compulsion to do something about it. From out there on the moon, international politics look so petty. You want to grab a politician by the scruff of the neck and drag him a quarter of a million miles out and say, ‘Look at that, you son of a bitch.’” — Apollo 14 astronaut Edgar Mitchell