Add tests for Table.apply error handling (#476)

Author: deriiinjv

tests/test_table_apply_errors.py

@@ -0,0 +1,21 @@
+import pytest
+from datascience import Table
+
+def test_apply_non_callable():
+    table = Table().with_columns("numbers", [1, 2, 3])
+    with pytest.raises(TypeError):
+        table.apply(123, "numbers")
+
+def test_apply_invalid_column_name():
+    table = Table().with_columns("numbers", [1, 2, 3])
+    with pytest.raises(ValueError):
+        table.apply(lambda x: x, "non_existent_column")
+
+def test_apply_function_returns_invalid_type():
+    table = Table().with_columns("numbers", [1, 2, 3])
+
+    def bad_fn(x):
+        return list(range(x))  
+    with pytest.raises(Exception):
+        table.apply(bad_fn, "numbers")
+