Do not emit an error when building outside of git

generated/meson.build

@@ -1,6 +1,7 @@
 version_override = get_option('override-version')
 if version_override == ''
-  version_header = vcs_tag(command: ['git', 'describe', '--dirty', '--broken'], input: 'version.hh.in', output: 'version.hh', fallback: meson.project_version())
+  # See the contents of meson_git_describe_wrapper.sh for explanation of its use
+  version_header = vcs_tag(command: 'meson_git_describe_wrapper.sh', input: 'version.hh.in', output: 'version.hh', fallback: meson.project_version())
 else
   conf_data = configuration_data()
   conf_data.set('VCS_TAG', version_override)

generated/meson_git_describe_wrapper.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+# The following command would normally print an error message if not run in a
+# git repository (e.g. when run in an extracted release archive, which doesn't
+# include git history).
+# J4dd's build system is configured to handle git failures well. If git isn't
+# available or if we're not in a git repository, version.txt is used to
+# determine the version.
+# Because this behavior is fully supported, printing an error message would only
+# confuse the user, because the error message implies that something is wrong.
+exec git describe --dirty --broken 2> /dev/null