[libhandy/libhandy-1-6] dist-data: Error out if it can't find docs

[Alexander Mikhaylenko <alexm src gnome org>]

commit 3420349b99acda31423c12de0a56636758d035bd
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Fri Aug 5 19:10:42 2022 +0400

    dist-data: Error out if it can't find docs
    
    The purpose of that script is to include pre-built docs into the tarball,
    which relies on docs having been manually built beforehand.
    
    This step is easy to miss, so visibly fail instead of continuing with an
    incomplete tarball.
    
    
    (cherry picked from commit 575d1af95427183aad778107b6c27fb8ccabbedc)

 build-aux/meson/dist-data.py | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/build-aux/meson/dist-data.py b/build-aux/meson/dist-data.py
index 1e5b3db8..b1eb237c 100644
--- a/build-aux/meson/dist-data.py
+++ b/build-aux/meson/dist-data.py
@@ -3,6 +3,7 @@
 import os
 import shutil
 import subprocess
+import sys
 
 from pathlib import PurePath
 
@@ -19,3 +20,5 @@ for reference in references:
     if os.path.isdir(src_path):
         dst_path = os.path.join(distroot, reference)
         shutil.copytree(src_path, dst_path)
+    else:
+        sys.exit("Documentation not found. Please pass -Dgtk_doc=true and to Meson and run ninja once.")