data loaders fail if they are in a subdirectory

[Fil]

docs/data/temp.csv.js

node:internal/process/promises:289
            triggerUncaughtException(err, true /* fromPromise */);
            ^

[Error: ENOENT: no such file or directory, rename '.observablehq/cache/data/temp.csv.27535' -> 'docs/.observablehq/cache/data/temp.csv.json'] {
  errno: -2,
  code: 'ENOENT',
  syscall: 'rename',
  path: '.observablehq/cache/data/temp.csv.27535',
  dest: 'docs/.observablehq/cache/data/temp.csv.json'
}