Check for MACS2 before splitting file

[AmelZulji]

When calling peaks using:

peaks <- CallPeaks(
  object = seu,
  group.by = "cell_type",
  macs2.path = "wrong_path"
)

splitting fragments will start before checking whether specified macs2.path points to existing instance of MACS2. It would be nice to first check for MACS2.

[timoast]

What version are you using? This should indeed be happening before splitting files: https://github.com/stuart-lab/signac/blob/8b98f63f89fb988fcfd5e1be6af6de316353008c/R/peaks.R#L80-L89

[timoast]

Ah, nevermind, I see what you're saying. We only check if there is a path, not that there's a functional MACS at that path. Ok, we can try to add that check.

[AmelZulji]

Thank you!