Don't cache NULL error returns from Jolpica

[Copilot]

When Jolpica is unreachable, load_* functions return NULL. memoise treats NULL as a valid return value and caches it — so retrying the same call returns the cached failure instead of hitting the network again.

Approach

memoise stores results via withVisible(), so a NULL return is stored as list(value = NULL, visible = ...). A thin cache wrapper intercepts $set() and silently drops writes where value$value is NULL, causing memoise to see a cache miss on the next call and re-execute the function.

null_filtering_cache <- function(cache) {
  list(
    set = function(key, value) {
      if (is.list(value) && is.null(value$value)) return(invisible(NULL))
      invisible(cache$set(key, value))
    },
    # all other methods delegate unchanged
    ...
  )
}

Changes

• R/zzz.R — Added null_filtering_cache() wrapper; applied to both cache_disk and cache_mem in .onLoad. All 14 memoised functions benefit automatically. The functions remain proper memoised-class objects, so has_cache(), forget(), and clear_f1_cache() are unaffected.
• tests/testthat/test-utils.R — Unit tests for null_filtering_cache() covering NULL suppression and delegation of other cache methods.
• tests/testthat/test-load_laps.R — Asserts has_cache(load_laps)(2021, 1) returns FALSE after a failed (no-network) call.
• .github/workflows/copilot-setup-steps.yml — R + Python environment setup for the Copilot agent.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/r-lib/memoise/contents/R
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)