fix: conf.i18n.add_missing_translations the right way (#1409)

- evaluate the switch first in any conditions
- missing evaluation of `add_missing_translations` in {% translate ...
%} constructs

src/viur/core/i18n.py

@@ -202,7 +202,7 @@ def __init__(
         self.public = public
         self.filename, self.lineno = None, None
 
-        if self.key not in systemTranslations and conf.i18n.add_missing_translations:
+        if conf.i18n.add_missing_translations and self.key not in systemTranslations:
             # This translation seems to be new and should be added
             for frame, line in traceback.walk_stack(sys._getframe(0).f_back):
                 if self.filename is None:
@@ -227,7 +227,7 @@ def __str__(self) -> str:
         if self.translationCache is None:
             global systemTranslations
 
-            if self.key not in systemTranslations and conf.i18n.add_missing_translations:
+            if conf.i18n.add_missing_translations and self.key not in systemTranslations:
                 # This translation seems to be new and should be added
 
                 add_missing_translation(
@@ -344,7 +344,7 @@ def parse(self, parser):
         tr_key = args[0].lower()
         public = kwargs.pop("_public_", False) or False
 
-        if tr_key not in systemTranslations:
+        if conf.i18n.add_missing_translations and tr_key not in systemTranslations:
             add_missing_translation(
                 key=tr_key,
                 hint=args[1],