it would be nice if there was a button to stop the mlc from running automatically. For example when I am writing a new program (read: writing code that produces a lot of errors) I don't want the mlc to run every tick (Sure I can just set delay to be really high but then I would have to change it back and forth). Similarly if I do something outside of the mlc to break it and causes errors, I could just turn off the mlc instead of deleting the object/the code.

Won't just putting out = {} on the last line of the code do that?

Or I guess another reasonable solution would be to disconnect its outputs temporarily, as you'd do with any other combinator(s).

I could just turn off the mlc instead of deleting the object/the code.

That's also easy to fix with presets - just click one of the number-buttons above to save code there and flush it, then restore back when needed.

when I am writing a new program (read: writing code that produces a lot of errors) I don't want the mlc to run every tick

Also note that it doesn't really run anything or load lua code in any way until you press "save".
Myself, I just write lua code in a nice text editor outside of factorio, and deliberately removed some rich-editing features from textbox here, because of how they made straightforward copy-pasting from there harder, with auto-formatting and such nonsense.
Basically, as description on the mod page suggests - use a proper editor for code, this is a textbox for minor tweaks or adding couple lines only, not Vim/Emacs or Lua IDE of some kind, and can never be.

Just put line in beginning of code and press save, then do calm editing..

do return end