attempt at better error recovery

- I often find that opening up driver.love and sending any message gets
  my app unwedged. Retrying should be easy. Just press a key.
- There's really no reason for the app to become unresponsive while
  waiting for code changes.

This approach tries to address both. Press any key to retry, or show the
error right on the window while I whip out driver.love. You can also
copy the message to the clipboard by hitting 'c'.

Drawbacks of this approach:
  - nobody's going to read the message. I myself didn't notice the
    default support for copying the error message for _months_.
  - more complexity for anyone reading the code to parse. More stuff
    that can go wrong. Any errors within the handler will crash the app
    hard. (Though now there's less code in the handler, so maybe this is
    an improvement on that score.)

The best plan is still to not rely on this too much. Don't ship bugs.

live.lua

@@ -296,25 +296,18 @@ end
 
 -- return nil to continue the event loop, non-nil to quit
 function live.handle_error(err)
-  -- draw a pause indicator on screen
-  love.graphics.setColor(1,0,0)
-  love.graphics.rectangle('fill', 10,10, 3,10)
-  love.graphics.rectangle('fill', 16,10, 3,10)
-  love.graphics.present()
-  -- print stack trace here just in case we ran the app through a terminal
-  local stack_trace = debug.traceback('Error: '..tostring(err), --[[stack frame]]2):gsub('\n[^\n]+$', '')
-  print(stack_trace)
-  print('Look in the driver for options to investigate further.')
-  print("(You probably can't close the app window at this point. If you don't have the driver set up, you might need to force-quit.)")
-  -- send stack trace to driver and wait for a response
+  Mode = 'error'
+  local stack_trace = debug.traceback('Error: ' .. tostring(err), --[[stack frame]]2):gsub('\n[^\n]+$', '')
   live.send_run_time_error_to_driver(stack_trace)
-  local buf
-  repeat
-    buf = live.receive_from_driver()
-    love.timer.sleep(0.001)
-  until buf
-  if buf == 'QUIT' then
-    return true
+  Error_message = 'Something is wrong. Sorry!\n\n'..stack_trace..'\n\n'..
+    "(Note: function names above don't include outer tables. So functions like on.draw might show up as just 'draw', etc.)\n\n"..
+    'Options:\n'..
+    '- press "ctrl+c" (without the quotes) to copy this message to your clipboard to send to me: ak@akkartik.com\n'..
+    '- press any other key to retry, see if things start working again\n'..
+    '- run driver.love to try to fix it yourself. As you do, feel free to ask me questions: ak@akkartik.com\n'
+  Error_count = Error_count+1
+  if Error_count > 1 then
+    Error_message = Error_message..('\n\nThis is error #%d in this session; things will probably not improve in this session. Please copy the message and send it to me: ak@akkartik.com.'):format(Error_count)
   end
-  live.run(buf)
+  print(Error_message)
 end

main.lua

@@ -13,13 +13,19 @@ require 'edit'
 Editor_state = {}
 
 function App.version_check()
-  -- available modes: run, version_check
-  Mode = 'version_check'
+  -- available modes: run, error
+  Mode = 'run'
+  Error_message = nil
+  Error_count = 0
+  -- we'll reuse error mode on load for an initial version check
   Supported_versions = {'11.4', '11.3', '11.2', '11.1', '11.0'}  -- keep these sorted in descending order
   local major, minor = love.getVersion()
   Version = major..'.'..minor
-  if array.find(Supported_versions, Version) then
-    Mode = 'run'
+  if array.find(Supported_versions, Version) == nil then
+    Mode = 'error'
+    Error_message = ("This app doesn't support version %s; please use version %s. Press any key to try it with this version anyway."):format(Version, Supported_versions[1])
+    print(Error_message)
+    -- continue initializing everything; hopefully we won't have errors during initialization
   end
 end
 
@@ -139,48 +145,51 @@ function App.filedropped(file)
 end
 
 function App.draw()
-  if Mode == 'version_check' then
-    love.graphics.setColor(1,1,0)
-    love.graphics.rectangle('fill', 30,30, 400,400)
-    love.graphics.setColor(0,0,0)
-    love.graphics.printf(("This app doesn't support version %s; please use version %s. Press any key to try it with this version anyway."):format(Version, Supported_versions[1]), 40,40, 400)
+  if Mode == 'error' then
+    love.graphics.setColor(0,0,1)
+    love.graphics.rectangle('fill', 0,0, App.screen.width, App.screen.height)
+    love.graphics.setColor(1,1,1)
+    love.graphics.printf(Error_message, 40,40, 600)
     return
   end
   if on.draw then on.draw() end
 end
 
 function App.update(dt)
-  if Mode == 'version_check' then return end
+  if Mode == 'error' then return end
   Current_time = Current_time + dt
   -- some hysteresis while resizing
   if Current_time < Last_resize_time + 0.1 then
     return
   end
   Cursor_time = Cursor_time + dt
+  -- listen for commands in both 'error' and 'run' modes
   live.update(dt)
-  if on.update then on.update(dt) end
+  if Mode == 'run' then
+    if on.update then on.update(dt) end
+  end
 end
 
 function App.mousepressed(x,y, mouse_button)
-  if Mode == 'version_check' then return end
+  if Mode == 'error' then return end
   Cursor_time = 0  -- ensure cursor is visible immediately after it moves
   if on.mouse_press then on.mouse_press(x,y, mouse_button) end
 end
 
 function App.mousereleased(x,y, mouse_button)
-  if Mode == 'version_check' then return end
+  if Mode == 'error' then return end
   Cursor_time = 0  -- ensure cursor is visible immediately after it moves
   if on.mouse_release then on.mouse_release(x,y, mouse_button) end
 end
 
 function App.wheelmoved(dx,dy)
-  if Mode == 'version_check' then return end
+  if Mode == 'error' then return end
   Cursor_time = 0  -- ensure cursor is visible immediately after it moves
   if on.mouse_wheel_move then on.mouse_wheel_move(dx,dy) end
 end
 
 function App.focus(in_focus)
-  if Mode == 'version_check' then return end
+  if Mode == 'error' then return end
   if in_focus then
     Last_focus_time = Current_time
   end
@@ -195,7 +204,12 @@ end
 -- App.keypressed is defined in keychord.lua
 
 function App.keychord_press(chord, key)
-  if Mode == 'version_check' then return end
+  if Mode == 'error' then
+    if chord == 'C-c' then
+      love.system.setClipboardText(Error_message)
+    end
+    return
+  end
   -- ignore events for some time after window in focus (mostly alt-tab)
   if Current_time < Last_focus_time + 0.01 then
     return
@@ -205,7 +219,7 @@ function App.keychord_press(chord, key)
 end
 
 function App.textinput(t)
-  if Mode == 'version_check' then return end
+  if Mode == 'error' then return end
   -- ignore events for some time after window in focus (mostly alt-tab)
   if Current_time < Last_focus_time + 0.01 then
     return
@@ -215,7 +229,7 @@ function App.textinput(t)
 end
 
 function App.keyreleased(key, scancode)
-  if Mode == 'version_check' then
+  if Mode == 'error' then
     Mode = 'run'
     return
   end