Move edit_runner into its own module

I've a few more features I'd like to add to it. Moving it out makes it
slightly easier to maintain.

projects/core/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/edit_runner.lua

@@ -0,0 +1,58 @@
+-- SPDX-FileCopyrightText: 2025 The CC: Tweaked Developers
+--
+-- SPDX-License-Identifier: MPL-2.0
+
+--[[- Launches a program, reports any errors, and prompts the user to close the
+tab.
+
+> [!DANGER]
+> This is an internal module and SHOULD NOT be used in your own code. It may
+> be removed or changed at any time.
+
+This is used by the `edit` program to launch the running code.
+
+@tparam string title The title of the multishell tab.
+@tparam string path The path to the file.
+@tparam string contents The contents of the file.
+
+@local
+]]
+return function(title, path, contents)
+    multishell.setTitle(multishell.getCurrent(), title)
+    local current = term.current()
+    local fn, err = load(contents, path, nil, _ENV)
+    if fn then
+        local exception = require "cc.internal.exception"
+        local ok, err, co = exception.try(fn)
+
+        term.redirect(current)
+        term.setTextColor(term.isColour() and colours.yellow or colours.white)
+        term.setBackgroundColor(colours.black)
+        term.setCursorBlink(false)
+
+        if not ok then
+            printError(err)
+            exception.report(err, co, { [path] = contents })
+        end
+    else
+        local parser = require "cc.internal.syntax"
+        if parser.parse_program(contents) then printError(err) end
+    end
+
+    local message = "Press any key to continue."
+    local _, y = term.getCursorPos()
+    local w, h = term.getSize()
+    local wrapped = require("cc.strings").wrap(message, w)
+
+    term.setTextColor(colours.white)
+    term.setBackgroundColor(colours.black)
+
+    local start_y = h - #wrapped + 1
+    if y >= start_y then term.scroll(y - start_y + 1) end
+    for i = 1, #wrapped do
+        term.setCursorPos(1, start_y + i - 1)
+        term.write(wrapped[i])
+    end
+    os.pullEvent('key')
+    require "cc.internal.event".discard_char()
+end

projects/core/src/main/resources/data/computercraft/lua/rom/programs/edit.lua

@@ -53,44 +53,6 @@ else
     errorColour = colours.white
 end
 
-local runHandler = [[multishell.setTitle(multishell.getCurrent(), %q)
-local current = term.current()
-local contents, name = %q, %q
-local fn, err = load(contents, name, nil, _ENV)
-if fn then
-    local exception = require "cc.internal.exception"
-    local ok, err, co = exception.try(fn, ...)
-
-    term.redirect(current)
-    term.setTextColor(term.isColour() and colours.yellow or colours.white)
-    term.setBackgroundColor(colours.black)
-    term.setCursorBlink(false)
-
-    if not ok then
-        printError(err)
-        exception.report(err, co, { [name] = contents })
-    end
-else
-    local parser = require "cc.internal.syntax"
-    if parser.parse_program(contents) then printError(err) end
-end
-
-local message = "Press any key to continue."
-if ok then message = "Program finished. " .. message end
-local _, y = term.getCursorPos()
-local w, h = term.getSize()
-local wrapped = require("cc.strings").wrap(message, w)
-
-local start_y = h - #wrapped + 1
-if y >= start_y then term.scroll(y - start_y + 1) end
-for i = 1, #wrapped do
-    term.setCursorPos(1, start_y + i - 1)
-    term.write(wrapped[i])
-end
-os.pullEvent('key')
-require "cc.internal.event".discard_char()
-]]
-
 -- Menus
 local bMenu = false
 local nMenuItem = 1
@@ -462,7 +424,8 @@ local tMenuFuncs = {
             return
         end
         local ok = save(sTempPath, function(file)
-            file.write(runHandler:format(sTitle, table.concat(tLines, "\n"), "@/" .. sPath))
+            local runHandler = [[return require("cc.internal.edit_runner")(%q, %q, %q)]]
+            file.write(runHandler:format(sTitle, "@/" .. sPath, table.concat(tLines, "\n")))
         end)
         if ok then
             local nTask = shell.openTab("/" .. sTempPath)