This is a first step towards handling OOM errors instead of just
crashing the program.
Now UDPServer's method `receive()` return memory allocation
errors explicitly with help of ErrorOr.
This removes one FIXME and make a bunch of new ones. :(
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *