inarray() is not a script command of Hercules (see the docs in doc/script_commands.txt) and is also not included in the "Array manipulation functions" script
You should either replace it with a for() loop or if you want to use Array manipulation functions you should use array_exists() like so:
// with Array manipulation functions:
if (!array_exists(.@unique_id, get_unique_id())) {
...
}
// with a for() loop:
.@size = getarraysize(.@unique_id);
for (.@k = 0; .@k < .@size; ++.@k) {
if (.@unique_id[.@k] == get_unique_id()) {
break;
}
...
}
Keep in mind that get_unique_id() is also not part of Hercules so if you don't have a plugin that provides it or source mods (not recommended) it will not work