fix issue rendering strips with missing style

Author: willmcgugan

src/textual/strip.py

@@ -659,9 +659,12 @@ def render(self, console: Console) -> str:
             render = Style.render
             self._render_cache = "".join(
                 [
-                    render(style, text, color_system=color_system)
+                    (
+                        text
+                        if style is None
+                        else render(style, text, color_system=color_system)
+                    )
                     for text, style, _ in self._segments
-                    if style is not None
                 ]
             )
         return self._render_cache

tests/snapshot_tests/test_snapshots.py

@@ -29,6 +29,8 @@
 from textual.reactive import var
 from textual.renderables.gradient import LinearGradient
 from textual.screen import ModalScreen, Screen
+from textual.strip import Strip
+from textual.widget import Widget
 from textual.widgets import (
     Button,
     Collapsible,

tests/test_strip.py

@@ -1,4 +1,5 @@
 import pytest
+from rich.console import Console
 from rich.segment import Segment
 from rich.style import Style
 
@@ -196,3 +197,9 @@ def test_text():
     assert Strip([]).text == ""
     assert Strip([Segment("foo")]).text == "foo"
     assert Strip([Segment("foo"), Segment("bar")]).text == "foobar"
+
+
+def test_render_with_missing_style() -> None:
+    """Test that render with segments that omit a style still work."""
+    strip = Strip([Segment("Hello")])
+    assert strip.render(Console()) == "Hello"