Introduce the console command /fac, the same as /c but accessible and…

… in the Factorio Access environment

If you are sighted /c is fine. If you are blind /c is wrap things in print and then
go check the launcher output, and probably also throw serpent around that.  /fac instead
handles figuring out the common cases of when to use serpent, overrides lua print to work with the launcher, and lets
the specified code run in the FA environment (e.g. it can see storage).

Crashes are guarded with pcall on a best effort basis, but there is probably still a way to crash this.  Still, it's for devs not players.

control.lua

@@ -30,6 +30,7 @@ local fa_warnings = require("scripts.warnings")
 local fa_circuits = require("scripts.circuit-networks")
 local fa_kk = require("scripts.kruise-kontrol-wrapper")
 local fa_quickbar = require("scripts.quickbar")
+local FaCommands = require("scripts.fa-commands")
 local Consts = require("scripts.consts")
 local Research = require("scripts.research")
 local Rulers = require("scripts.rulers")
@@ -8314,6 +8315,9 @@ script.on_event(defines.events.on_console_chat, function(event)
 end)
 
 script.on_event(defines.events.on_console_command, function(event)
+   -- For our own commands, we handle the speaking and must not read here.
+   if FaCommands.COMMANDS[event.command] then return end
+
    local speaker = game.get_player(event.player_index).name
    if speaker == nil or speaker == "" then speaker = "Player" end
    for pindex, player in pairs(players) do

scripts/fa-commands.lua

@@ -0,0 +1,94 @@
+--[[
+Custom console commands, primarily for debugging and internal use.  Docs with
+the handlers in this file.
+
+Handlers registered by this file are exported and not announced through our
+normal handling.  This is because the launcher cannot handle queueing.  We need
+the mod to be silent.
+]]
+
+local mod = {}
+
+--[[
+/fac <script>
+
+Exactrly the same as /c, but accessible without fiddling around. It:
+
+- Captures return values, then speaks them through serpent:
+  - Tries to run the code wrapped in a function, with return prepended
+  - Otherwise, runs the code directly, and uses whatever the chunk returns.
+- Overrides Lua print to go to speech, and concatenates everything up so that we
+  don't "trip" over the announcements.
+- Makes printout available, as a mocked version that will just call to print
+  (IMPORTANT: only works on the current player; pindex is ignored).
+- Announces errors, with tracebacks, using pcall.
+
+Also due to launcher limitations, "print" here doesn't do newlines.  That'll
+cause the launcher to not read right.
+]]
+---@param cmd CustomCommandData
+function cmd_fac(cmd)
+   local pindex = cmd.player_index
+   local script = cmd.parameter
+
+   if not cmd.parameter or cmd.parameter == "" then
+      printout("A script is required", pindex)
+      return
+   end
+
+   local printbuffer = ""
+
+   local function print_override(...)
+      -- Send a copy to launcher stdout for debugging.
+      print(...)
+
+      local args = table.pack(...)
+      for i = 1, args.n do
+         printbuffer = printbuffer .. tostring(args[i]) .. " "
+      end
+   end
+
+   local with_return = "return " .. script
+
+   local environment = {}
+   for k, v in pairs(_ENV) do
+      environment[k] = v
+   end
+   environment.print = print_override
+   environment.printout = function(arg, pindex)
+      print_override(arg, "for pindex", pindex)
+   end
+
+   local chunk, err = load(with_return, "=(load)", "t", environment)
+   if not chunk then
+      chunk, err = load(cmd.parameter, "=(load)", "t", environment)
+      if err then
+         printout(err, pindex)
+         print(err)
+         return
+      end
+   end
+
+   local _good, val = pcall(function()
+      local r = chunk()
+      return serpent.line(r, { nocode = true })
+   end)
+
+   print_override(val)
+
+   print("Printbuffer is", printbuffer)
+   printout(printbuffer, pindex)
+end
+
+mod.COMMANDS = {
+   fac = {
+      help = "See commands.lua",
+      handler = cmd_fac,
+   },
+}
+
+for name, args in pairs(mod.COMMANDS) do
+   commands.add_command(name, args.help, args.handler)
+end
+
+return mod