diff --git a/libretranslate/app.py b/libretranslate/app.py
index a5a77a8..c888861 100644
--- a/libretranslate/app.py
+++ b/libretranslate/app.py
@@ -644,6 +644,7 @@ def create_app(args):
                         }
                     )
         except Exception as e:
+            raise e
             abort(500, description=_("Cannot translate text: %(text)s", text=str(e)))
 
     @bp.post("/translate_file")
diff --git a/libretranslate/language.py b/libretranslate/language.py
index 86921bc..44f926f 100644
--- a/libretranslate/language.py
+++ b/libretranslate/language.py
@@ -107,6 +107,9 @@ def improve_translation_formatting(source, translation, improve_punctuation=True
     if source.isupper():
         return translation.upper()
 
+    if len(translation) == 0:
+        return source
+
     if source[0].islower():
         return translation[0].lower() + translation[1:]