Fix some typing issues

src/textual/_two_way_dict.py

@@ -27,29 +27,38 @@ class TwoWayDict(Generic[Key, Value]):
         self._forward.__delitem__(key)
         self._reverse.__delitem__(value)
 
-    def get(self, key: Key, default: Value | None = None) -> Value:
+    def get(self, key: Key) -> Value:
         """Given a key, efficiently lookup and return the associated value.
 
         Args:
             key: The key
-            default: The default return value if not found. Defaults to None.
 
         Returns:
             The value
         """
-        return self._forward.get(key, default)
+        return self._forward.get(key)
 
-    def get_key(self, value: Value, default: Key | None = None) -> Key:
+    def get_key(self, value: Value) -> Key:
         """Given a value, efficiently lookup and return the associated key.
 
         Args:
             value: The value
-            default: The default return value if not found. Defaults to None.
 
         Returns:
             The key
         """
-        return self._reverse.get(value, default)
+        return self._reverse.get(value)
+
+    def contains_value(self, value: Value) -> bool:
+        """Check if `value` is a value within this TwoWayDict.
+
+        Args:
+            value: The value to check.
+
+        Returns:
+            True if the value is within the values of this dict.
+        """
+        return value in self._reverse
 
     def __len__(self):
         return len(self._forward)

src/textual/widgets/_data_table.py

@@ -1113,7 +1113,7 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
         column_keys = [
             self._column_locations.get_key(index) for index in column_indices
         ]
-        ordered_columns = [self.columns.get(key) for key in column_keys]
+        ordered_columns = [self.columns[key] for key in column_keys]
         return ordered_columns
 
     @property
@@ -1123,7 +1123,7 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
         ordered_rows = []
         for row_index in row_indices:
             row_key = self._row_locations.get_key(row_index)
-            row = self.rows.get(row_key)
+            row = self.rows[row_key]
             ordered_rows.append(row)
         return ordered_rows
 
@@ -1279,7 +1279,11 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
             else:
                 return False
 
-        row_index = self._row_locations.get(row_key, -1)
+        if row_key in self._row_locations:
+            row_index = self._row_locations.get(row_key)
+        else:
+            row_index = -1
+
         render_cell = self._render_cell
         if self.fixed_columns:
             fixed_style = self.get_component_styles("datatable--fixed").rich_style