Silently fails if server misconfigured.

[gpcf]

Forceload anchor does not write anything in the flm.json file after placing the anchor. I'm running the 0.4.15 version bundled with Debian sid.
Contents of flm.json:
return {}

[gpcf]

It was a server configuration issue, I raised max_forceload_blocks to 200 and then it worked. It should display a warning message if the server configuration does not allow forceloading.