Add some error handling to async response handler

We only want to read data in case of POLLIN or POLLHUP. Not POLLNVAL or
select error.

We always want to remove the handler, so it doesn't get called in an
infinite loop when error is nval or err.

In zsh source, see main zle event loop in zle_main.c raw_getbyte
function.

src/async.zsh

@@ -41,10 +41,14 @@ _zsh_autosuggest_async_request() {
 # First arg will be fd ready for reading
 # Second arg will be passed in case of error
 _zsh_autosuggest_async_response() {
-	# Read everything from the fd and give it as a suggestion
-	zle autosuggest-suggest -- "$(cat <&$1)"
+	if [[ -z "$2" || "$2" == "hup" ]]; then
+		# Read everything from the fd and give it as a suggestion
+		zle autosuggest-suggest -- "$(cat <&$1)"
 
-	# Remove the handler and close the fd
+		# Close the fd
+		exec {1}<&-
+	fi
+
+	# Always remove the handler
 	zle -F "$1"
-	exec {1}<&-
 }

zsh-autosuggestions.zsh

@@ -720,12 +720,16 @@ _zsh_autosuggest_async_request() {
 # First arg will be fd ready for reading
 # Second arg will be passed in case of error
 _zsh_autosuggest_async_response() {
-	# Read everything from the fd and give it as a suggestion
-	zle autosuggest-suggest -- "$(cat <&$1)"
+	if [[ -z "$2" || "$2" == "hup" ]]; then
+		# Read everything from the fd and give it as a suggestion
+		zle autosuggest-suggest -- "$(cat <&$1)"
 
-	# Remove the handler and close the fd
+		# Close the fd
+		exec {1}<&-
+	fi
+
+	# Always remove the handler
 	zle -F "$1"
-	exec {1}<&-
 }
 
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