Prevent git errors from showing in command output

This would be a very rare case, but one time the git command failed, printing out an obscure "fatal" message to stderr which caused confusion.

config/application.rb

@@ -24,6 +24,7 @@ require_relative "../lib/open_food_network/i18n_config"
 require_relative '../lib/spree/core/environment'
 require_relative '../lib/spree/core/mail_interceptor'
 require_relative "../lib/i18n_digests"
+require_relative "../lib/git_utils"
 
 if defined?(Bundler)
   # If you precompile assets before deploying to production, use this line
@@ -34,8 +35,8 @@ end
 
 module Openfoodnetwork
   class Application < Rails::Application
-    # Store a description of the current version, with linebreak trimmed
-    config.x.git_version = `git describe --tags --dirty=-modified`.strip
+    # Store a description of the current version
+    config.x.git_version = GitUtils::git_version
 
     config.after_initialize do
       # We need this here because the test env file loads before the Spree engine is loaded

lib/git_utils.rb

@@ -0,0 +1,15 @@
+class GitUtils
+  # Generate a description of the git version based on latest tag.
+  # Eg: "v4.4.4-156-g8afcd82-modified"
+  #  - tag name
+  #  - number of commits since tag
+  #  - commit ID
+  #  - "modified" if uncommitted changes
+  #
+  def self.git_version
+    # Capture stderr so that confusing errors aren't shown in comand output
+    stdout, _stderr, _status = Open3.capture3("git describe --tags --dirty=-modified")
+    # Strip trailing linebreak
+    stdout.strip
+  end
+end