Only print the id attribute if it’s a string

If it’s something weird like an instance of a Python object let’s ignore
it (else we get invalid HTML like
`id='<notifications_utils.columns.Cell object at 0x1126f4e80>'`).

app/templates/components/table.html

@@ -45,7 +45,7 @@
 {%- endmacro %}
 
 {% macro row(id=None) -%}
-  <tr class="table-row" {% if id %}id="{{id}}"{% endif %}>
+  <tr class="table-row" {% if id and id is string %}id="{{id}}"{% endif %}>
     {{ caller() }}
   </tr>
 {%- endmacro %}

tests/app/main/views/test_send.py

@@ -704,6 +704,7 @@ def test_upload_valid_csv_shows_preview_and_table(
     ]):
         for index, cell in enumerate(row):
             row = page.select('table tbody tr')[row_index]
+            assert 'id' not in row
             assert normalize_spaces(str(row.select('td')[index + 1])) == cell