Raise an error only when `require_master_key` is specified

To prevent errors from being raise in environments where credentials
is unnecessary.

Context: https://github.com/rails/rails/issues/31283#issuecomment-348801489

Fixes #31283

1 files changed, 9 insertions, 2 deletions

diff --git a/railties/lib/rails/commands/credentials/credentials_command.rb b/railties/lib/rails/commands/credentials/credentials_command.rb
index 8085f07c2b..385d3976da 100644
--- a/railties/lib/rails/commands/credentials/credentials_command.rb
+++ b/railties/lib/rails/commands/credentials/credentials_command.rb
@@ -33,8 +33,7 @@ module Rails
       def show
         require_application_and_environment!
 
-        say Rails.application.credentials.read.presence ||
-          "No credentials have been added yet. Use bin/rails credentials:edit to change that."
+        say Rails.application.credentials.read.presence || missing_credentials_message
       end
 
       private
@@ -67,6 +66,14 @@ module Rails
 
           Rails::Generators::CredentialsGenerator.new
         end
+
+        def missing_credentials_message
+          if Rails.application.credentials.key.nil?
+            "Missing master key to decrypt credentials. See bin/rails credentials:help"
+          else
+            "No credentials have been added yet. Use bin/rails credentials:edit to change that."
+          end
+        end
     end
   end
 end