fix(auto-fallback): prevent infinite loop if npx disappears

auto-fallback.js

@@ -10,7 +10,13 @@ command_not_found_${opts.isBash ? 'handle' : 'handler'}() {
     >&2 echo "${Y`command not found: ${'$1'}`}"
     return 127
   fi
-  echo "${Y`${'$1'} not found. Trying with npx...`}" >&2
+  if which npx > /dev/null; then
+    echo "${Y`${'$1'} not found. Trying with npx...`}" >&2
+  else
+    return 127
+  fi
+  if
+  which npx > /dev/null
   if ! [[ $1 =~ @ ]]; then
     npx --no-install "$@"
   else
@@ -27,7 +33,11 @@ function __fish_command_not_found_on_interactive --on-event fish_prompt
   functions --erase __fish_command_not_found_setup
 
   function __fish_command_not_found_handler --on-event fish_command_not_found
-    echo "${Y`${'$argv[1]'} not found. Trying with npx...`}" >&2
+    if which npx > /dev/null
+        echo "${Y`${'$argv[1]'} not found. Trying with npx...`}" >&2
+    else
+        return 127
+    end
     if string match -q -r @ $argv[1]
         npx $argv
     else