GUI startup/locale. Changed so that if there's an error when setting …

…locale, it shows an error notification on the console and tries to continue. This is to address part of issue #3 on GitHub (comment 17 June 2024).

docs/config-examples/defaults.ini

@@ -57,9 +57,9 @@
 
 # language = language string (e.g. en_GB, en_US, fr)
 #       UI language. Note: the selected locale must be installed on the
-#       operating system, otherwise it will give an error and fail to
-#       start. (To enable a locale on Debian, edit the /etc/locale.gen
-#       file and then run (sudo) locale-gen.)
+#       operating system, otherwise it will show an error in the console
+#       and fall back to the default. (To enable a locale on Debian, edit
+#       the /etc/locale.gen file and then run (sudo) locale-gen.)
 #       Default: Use operating system locale
 
 # date_sep = string

pygenda/pygenda_gui.py

@@ -29,6 +29,7 @@
 from importlib import import_module
 from os import path as ospath
 from sys import stderr
+from pathlib import Path
 import signal
 import ctypes
 from typing import Optional, Tuple, List, Union, Any, Type
@@ -427,7 +428,15 @@ def _init_locale(cls) -> None:
         if isinstance(lang,str) and '.' not in lang:
             # Need to include encoding
             lang = (lang,'UTF-8')
-        locale.setlocale(locale.LC_ALL, lang)
+        try:
+            locale.setlocale(locale.LC_ALL, lang)
+        except locale.Error:
+            lang_dname = lang if isinstance(lang,str) else '.'.join(lang)
+            print("Error loading locale {:s} (not installed on OS?)".format(lang_dname), file=stderr)
+            if Path('/etc/debian_version').exists():
+                # Add extra info for users on Debian-like systems
+                print(" On Debian try: uncomment corresponding line in /etc/locale.gen & run locale-gen", file=stderr)
+            print(" Trying to continue with default locale...", file=stderr)
         locale.bindtextdomain('pygenda', cls._LOCALE_DIR)
         locale.textdomain('pygenda')