missing: adjust to new ARGV.formulae behavior

Since 25aefdd ("don't complain if args are empty"), ARGV.formulae does
not raise an exception; `brew missing` was relying on that to determine
what set of formulae to act on. Fix this, and also a typo.

Fixes Homebrew/homebrew#10617.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Contributions/examples/brew-missing.rb

@@ -16,15 +16,19 @@ def main
   # Names of outdated brews; they count as installed.
   outdated = Homebrew.outdated_brews.collect{ |b| b.name }
 
-  formuale_to_check = ARGV.formulae rescue installed_brews
+  formulae_to_check = if ARGV.named.empty?
+    installed_brews
+  else
+    ARGV.formulae
+  end
 
-  formuale_to_check.each do |f|
+  formulae_to_check.each do |f|
     missing_deps = f.recursive_deps.map{ |g| g.name }.uniq.reject do |dep_name|
       Formula.factory(dep_name).installed? or outdated.include?(dep_name)
     end
 
     unless missing_deps.empty?
-      print "#{f.name}: " if formuale_to_check.size > 1
+      print "#{f.name}: " if formulae_to_check.size > 1
       puts "#{missing_deps * ', '}"
     end
   end