message: Undo a bug of my own creation
diff: @@ -484,7 +484,7 @@ function evalInstr(instr: bril.Instruction, env: Env, heap:Heap<Value>, funcs: b
  case "load": {
  let ptr = getPtr(instr, env, 0);
  let val = heap.read(ptr.loc);
  - if (!val) {
  + if (val === undefined || val === null) {
  throw error(`Pointer ${instr.args[0]} points to uninitialized data`);
  } else {
  env.set(instr.dest, val);
  