Fix error message documentation

activesupport/lib/active_support/ordered_options.rb

@@ -24,7 +24,7 @@ module ActiveSupport
   # To raise an exception when the value is blank, append a
   # bang to the key name, like:
   #
-  #   h.dog! # => raises KeyError: key not found: :dog
+  #   h.dog! # => raises KeyError: :dog is blank
   #
   class OrderedOptions < Hash
     alias_method :_get, :[] # preserve the original #[] method
@@ -46,7 +46,7 @@ def method_missing(name, *args)
         bangs = name_string.chomp!("!")
 
         if bangs
-          fetch(name_string.to_sym).presence || raise(KeyError.new("#{name_string} is blank."))
+          fetch(name_string.to_sym).presence || raise(KeyError.new(":#{name_string} is blank"))
         else
           self[name_string]
         end

guides/source/security.md

@@ -1049,7 +1049,7 @@ If you want an exception to be raised when some key is blank, use the bang
 version:
 
 ```ruby
-Rails.application.credentials.some_api_key! # => raises KeyError: key not found: :some_api_key
+Rails.application.credentials.some_api_key! # => raises KeyError: :some_api_key is blank
 ```
 
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