Error_message = debug.traceback('Error: ' .. tostring(err), --[[stack frame]]2)

  local callstack = debug.traceback('', --[[stack frame]]2)
  Error_message = 'Error: ' .. tostring(err)..'\n'..clean_up_callstack(callstack)

-- I tend to read code from files myself (say using love.filesystem calls)
-- rather than offload that to load().
-- Functions compiled in this manner have ugly filenames of the form [string "filename"]
-- This function cleans out this cruft from error callstacks.
function clean_up_callstack(callstack)
  local frames = {}
  print(callstack)
  for frame in string.gmatch(callstack, '[^\n]+\n*') do
    local line = frame:gsub('^%s*(.-)\n?$', '%1')
    local filename, rest = line:match('([^:]*):(.*)')
    local core_filename = filename:match('^%[string "(.*)"%]$')
    -- pass through frames that don't match this format
    -- this includes the initial line "stack traceback:"
    local new_frame = (core_filename or filename)..':'..rest
    table.insert(frames, new_frame)
  end
  -- the initial "stack traceback:" line was unindented and remains so
  return table.concat(frames, '\n\t')
end