datasource: fix get_id_by_option_text with None result (#67409)

tests/form_pages/test_live.py

@@ -12,6 +12,7 @@ from wcs.blocks import BlockDef
 from wcs.carddef import CardDef
 from wcs.data_sources import NamedDataSource
 from wcs.formdef import FormDef
+from wcs.qommon import misc
 from wcs.wf.form import WorkflowFormFieldsFormDef
 from wcs.workflows import Workflow
 
@@ -1182,6 +1183,14 @@ def test_field_live_item_datasource_prefill_with_request_with_q(urlopen, pub):
     # check it has ?q=
     assert urlopen.call_args[0][0] == 'http://remote.example.net/json?plop=&q=deux'
 
+    urlopen.side_effect = misc.ConnectionError('...')
+    # no error
+    app.post(
+        '/foo/live?modified_field_id=init&prefilled_1=on&prefilled_2=on',
+        params=resp.form.submit_fields(),
+        status=200,
+    )
+
 
 def test_field_live_block_string_prefill(pub, http_requests):
     FormDef.wipe()

wcs/data_sources.py

@@ -217,7 +217,7 @@ def get_id_by_option_text(data_source, text_value):
             items = get_structured_items(data_source.extended_data_source, include_disabled=False)
 
         # fallback to iterating on all options
-        for option in items:
+        for option in items or []:
             # get raw value from display value
             if option['text'] == text_value:
                 return str(option['id'])