fix: prevent OIDC/SAML form crashes when editing a user source (baserow#5242)

---------

Co-authored-by: Jeremie Pardou <571533+jrmi@users.noreply.github.com>

Author: jonadeline

changelog/entries/unreleased/bug/5226_prevent_oidc_saml_form_crashes_when_editing_a_user_source.json

@@ -0,0 +1,9 @@
+{
+  "type": "bug",
+  "message": "prevent OIDC/SAML form crashes when editing a user source in the application builder",
+  "issue_origin": "github",
+  "issue_number": 5226,
+  "domain": "builder",
+  "bullet_points": [],
+  "created_at": "2026-04-21"
+}

web-frontend/modules/builder/components/userSource/UpdateUserSourceForm.vue

@@ -77,7 +77,7 @@
           >
             <component
               :is="appAuthType.formComponent"
-              v-if="hasAtLeastOneOfThisType(appAuthType)"
+              v-if="hasAtLeastOneOfThisType(appAuthType) && fullValues?.type"
               :ref="`authProviderForm`"
               excluded-form
               :application="builder"
@@ -131,7 +131,7 @@ export default {
         name: '',
         auth_providers: [],
       },
-      fullValues: {},
+      fullValues: null,
     }
   },
   computed: {