add check for version in the-basics example (#2459)

[etc/vim.git] / src / blackd / __init__.py

diff --git a/src/blackd/__init__.py b/src/blackd/__init__.py
index 3e2a7e7c30f3eb3ed18d51bd18b4322069b588c3..d062303fd10d4f3190de861cfb5a4ddd42f2ac0a 100644 (file)
--- a/src/blackd/__init__.py
+++ b/src/blackd/__init__.py
@@ -1,6 +1,5 @@
 import asyncio
 import logging
-import sys
 from concurrent.futures import Executor, ProcessPoolExecutor
 from datetime import datetime
 from functools import partial
@@ -11,13 +10,11 @@ try:
     from aiohttp import web
     import aiohttp_cors
 except ImportError as ie:
-    print(
+    raise ImportError(
         f"aiohttp dependency is not installed: {ie}. "
         + "Please re-install black with the '[d]' extra install "
-        + "to obtain aiohttp_cors: `pip install black[d]`",
-        file=sys.stderr,
-    )
-    sys.exit(-1)
+        + "to obtain aiohttp_cors: `pip install black[d]`"
+    ) from None
 
 import black
 from black.concurrency import maybe_install_uvloop
@@ -198,7 +195,7 @@ def parse_python_variant_header(value: str) -> Tuple[bool, Set[black.TargetVersi
                     raise InvalidVariantHeader(f"3.{minor} is not supported")
                 versions.add(black.TargetVersion[version_str])
             except (KeyError, ValueError):
-                raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'")
+                raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'") from None
         return False, versions