diff --git a/src/_pytest/_code/code.py b/src/_pytest/_code/code.py
index 9ec926620..dacc18d31 100644
--- a/src/_pytest/_code/code.py
+++ b/src/_pytest/_code/code.py
@@ -743,7 +743,11 @@ class FormattedExcinfo:
     ) -> List[str]:
         """Return formatted and marked up source lines."""
         lines = []
-        if source is None or line_index >= len(source.lines) or line_index < -len(source.lines):
+        if (
+            source is None
+            or line_index >= len(source.lines)
+            or line_index < -len(source.lines)
+        ):
             source = Source("???")
             line_index = 0
         if line_index < 0: