fix error class instantiation (#6634)

src/transformers/tokenization_bert_japanese.py

@@ -199,7 +199,7 @@ class MecabTokenizer:
         try:
             import fugashi
         except ModuleNotFoundError as error:
-            raise error(
+            raise error.__class__(
                 "You need to install fugashi to use MecabTokenizer."
                 "See https://pypi.org/project/fugashi/ for installation."
             )
@@ -211,7 +211,7 @@ class MecabTokenizer:
                 try:
                     import ipadic
                 except ModuleNotFoundError as error:
-                    raise error(
+                    raise error.__class__(
                         "The ipadic dictionary is not installed. "
                         "See https://github.com/polm/ipadic-py for installation."
                     )
@@ -222,7 +222,7 @@ class MecabTokenizer:
                 try:
                     import unidic_lite
                 except ModuleNotFoundError as error:
-                    raise error(
+                    raise error.__class__(
                         "The unidic_lite dictionary is not installed. "
                         "See https://github.com/polm/unidic-lite for installation."
                     )
@@ -233,7 +233,7 @@ class MecabTokenizer:
                 try:
                     import unidic
                 except ModuleNotFoundError as error:
-                    raise error(
+                    raise error.__class__(
                         "The unidic dictionary is not installed. "
                         "See https://github.com/polm/unidic-py for installation."
                     )