Idk what constraints you decided to use when programming the physics from scratch--but they are good ones implemented well! Doing this in a single weekend is even more impressive!
No engine deals with solving perfectly, thanks to delta-time, and from what I've seen in GDC talks, the most graceful undesired behavior is objects under constant collision slowly pushing into each other... as opposed to source engine boxes going crazy, skyrims ragdolls shooting into space, or at worst, no-clipping out of bounds. The fact you're getting 0 no-clips at the framerate of my poor old computer in a web browser is amazing honestly.
Funny story, I wanted to make a pinball game. If you run our game, you can see a cartridge called "Balatzee" on the shelf in the top left. Similarly it will spawn balls that drop and only wall collisions are implemented. The frame rate issues with love.js and my own amateur coding of constraints with 0 research meant having the game function well in a week would be impossible. You got waaaaaay farther than I did in less time! Seriously awesome job!