trapslisted

# Traps Every entry here was found as **working-looking code**. None of them throws. Most of them point somewhere other than their cause, which is why they are worth carrying: an agent can read a `.d.ts` and cannot read any of this. Use it two ways. **Symptom first** if something is already wrong; **the list** if you are about to write one of these. --- ## Symptom → cause | what you see | look at | |---|---| | a black or one-color screen | camera never framed · `sort()` never called · darkness at 1 with no lights · light field not on the pen · a canvas with no size · a fractional grid index | | the tap opens the thing *behind* the one under the finger | something reordered after `sort()`, or two collections and an offset | | taps land uphill or downhill of where the finger was, by more the higher the hill | `createInput` was never told about the terrain, so every `gx`/`gy` is the sea-level answer | | a sculpting brush slides off the far side of a hill while the hand holds still | the same, on ground that moves: the error tracks the height under the pointer | | something got placed at `NaN`, and no bounds check said anything | `onGround` unchecked on a system that *does* declare terrain | | taps miss on tall things specifically | `spriteVolume` called without the ground | | art floats above or sinks below its hill | `drawSprite`'s ground argument omitted | | a building renders near-black, or one glows all night | a palette slot used as the wrong kind — `ink` and `night` a