[FIX] web: add DomainSelector debugValue default value

Steps to reproduce:

- Install Events
- Activate debug mode
- Events > Config > Lead generation > Create

Traceback is raised.

The `debugValue` prop added in a29691bfd8 should be a string but doesn't
have a default value, and it is evaluated as `false` at runtime.

Solution:

Add default value for `debugValue`.

opw-3056391

closes odoo/odoo#112149

X-original-commit: bec8da1dc250a40b77d02bd5f487f12f5a857dde
Signed-off-by: Michaël Mattiello <mcm@odoo.com>

addons/web/static/src/views/fields/domain/domain_field.xml

@@ -10,7 +10,7 @@
                     readonly="props.readonly or props.editInDialog"
                     update.bind="update"
                     isDebugMode="!!env.debug"
-                    debugValue="props.value"
+                    debugValue="props.value || '[]'"
                     className="props.readonly ? 'o_read_mode' : 'o_edit_mode'"
                 />
                 <div class="o_field_domain_panel">