Fixed crash bug. Wide characters were sometimes causing an index out of range error. Now they are just treated as spaces.

tests/unit/test_pty_terminal_sequences.py

@@ -39,6 +39,26 @@ def test_private_sgr_sequence_from_fullscreen_apps_does_not_crash():
     assert screen["text"].splitlines()[0] == "X         "
 
 
+@pytest.mark.unit
+def test_overwritten_wide_character_stub_renders_as_space():
+    terminal = Terminal(4, 1, DummyProcessInput())
+
+    terminal.feed("界\rX".encode())
+    screen = terminal.get_screen_content()
+
+    assert screen["text"] == "X   "
+
+
+@pytest.mark.unit
+def test_wide_character_and_stub_keep_terminal_width():
+    terminal = Terminal(4, 1, DummyProcessInput())
+
+    terminal.feed("界".encode())
+    screen = terminal.get_screen_content()
+
+    assert screen["text"] == "界  "
+
+
 @pytest.mark.unit
 def test_optional_float_setting_uses_default_when_missing():
     settings_manager = type(