Immediately restart worker and relaunch tasks on crash

pure.zsh

@@ -199,6 +199,8 @@ prompt_pure_preprompt_render() {
 }
 
 prompt_pure_precmd() {
+	setopt localoptions noshwordsplit
+
 	# Check execution time and store it in a variable.
 	prompt_pure_check_cmd_exec_time
 	unset prompt_pure_cmd_timestamp
@@ -379,16 +381,22 @@ prompt_pure_async_renice() {
 	fi
 }
 
+prompt_pure_async_init() {
+	typeset -g prompt_pure_async_inited
+	if ((${prompt_pure_async_inited:-0})); then
+		return
+	fi
+	prompt_pure_async_inited=1
+	async_start_worker "prompt_pure" -u -n
+	async_register_callback "prompt_pure" prompt_pure_async_callback
+	async_worker_eval "prompt_pure" prompt_pure_async_renice
+}
+
 prompt_pure_async_tasks() {
 	setopt localoptions noshwordsplit
 
 	# Initialize the async worker.
-	((!${prompt_pure_async_init:-0})) && {
-		async_start_worker "prompt_pure" -u -n
-		async_register_callback "prompt_pure" prompt_pure_async_callback
-		typeset -g prompt_pure_async_init=1
-		async_job "prompt_pure" prompt_pure_async_renice
-	}
+	prompt_pure_async_init
 
 	# Update the current working directory of the async worker.
 	async_worker_eval "prompt_pure" builtin cd -q $PWD
@@ -467,17 +475,20 @@ prompt_pure_async_callback() {
 
 	case $job in
 		\[async])
-			# Error codes from zsh-async:
-			#     1 Corrupted worker output.
-			#     2 ZLE watcher detected an error on the worker fd.
-			#     3 Response from async_job when worker is missing.
-			#   130 Async worker exited, this should never happen in
-			#       Pure so the file descriptor is corrupted.
+			# Handle all the errors that could indicate a crashed
+			# async worker. See zsh-async documentation for the
+			# definition of the exit codes.
 			if (( code == 2 )) || (( code == 3 )) || (( code == 130 )); then
-				# Our worker died unexpectedly, recovery
-				# will happen on next prompt.
-				typeset -g prompt_pure_async_init=0
+				# Our worker died unexpectedly, try to recover immediately.
+				# TODO(mafredri): Do we need to handle next_pending
+				#                 and defer the restart?
+				typeset -g prompt_pure_async_inited=0
 				async_stop_worker prompt_pure
+				prompt_pure_async_init   # Reinit the worker.
+				prompt_pure_async_tasks  # Restart all tasks.
+
+				# Reset render state due to restart.
+				unset prompt_pure_async_render_requested
 			fi
 			;;
 		\[async/eval])