misc: fix submitter email lookup in case of unfilled block data (#53254)

tests/test_formdata.py

@@ -228,6 +228,7 @@ def test_get_submitter(pub, formdef):
     formdef.fields = [
         fields.StringField(id='0', label='email', varname='foo', prefill={'type': 'user', 'value': 'email'}),
         fields.BlockField(id='1', label='test', type='block:foobar', max_items=3, varname='block'),
+        fields.StringField(id='2', label='other'),
     ]
     formdef.store()
 
@@ -263,6 +264,9 @@ def test_get_submitter(pub, formdef):
     formdata.data = {'1': {}}
     assert formdef.get_submitter_email(formdata) is None
 
+    formdata.data = {'2': 'other'}
+    assert formdef.get_submitter_email(formdata) is None
+
     formdata.data = {
         '0': 'foo@localhost',
         '1': {

wcs/formdef.py

@@ -1352,7 +1352,7 @@ class FormDef(StorableObject):
                     if not is_user_field(subfield):
                         continue
                     v = formdata.data.get(field.id)
-                    if not v.get('data'):
+                    if not (v and v.get('data')):
                         continue
                     for data in v.get('data'):
                         w = data.get(subfield.id)