Add missing command col exists check

Author: Kissaki

needs-update/custom-completions/auto-generate/parse-fish.nu

@@ -11,6 +11,16 @@ def build-completions-from-pwd [] {
     }
 }
 
+# parse every .fish file in the source_dir directory and make a .nu completions file of it in target_dir
+def build-completions [source: path, target_dir: path] {
+    glob $source
+    | par-each { |src|
+        let out = ($src | path parse | update extension 'nu' | path join)
+        print $"building nushell completions from ($src) into ($out)…"
+        build-completion $src $out
+    }
+}
+
 # build a completion form a .fish file and generate a .nu file
 def build-completion [fish_file: path, nu_file: path] {
     open $fish_file | parse-fish | make-commands-completion | str join "\n\n" | save $nu_file
@@ -104,6 +114,7 @@ def cleanup_subcommands [] {
 def make-commands-completion [] {
     let fishes = $in
     $fishes
+    | where 'command' in ($fishes | columns)
     | get command
     | uniq         # command is cloned on every complete line
     | each { |command|