web/admin: fix *Test Forms not having a default for codemirrors

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

web/src/pages/property-mappings/PropertyMappingTestForm.ts

@@ -9,6 +9,7 @@ import { ifDefined } from "lit-html/directives/if-defined";
 import "../../elements/forms/HorizontalFormElement";
 import "../../elements/CodeMirror";
 import { PolicyTest } from "authentik-api/src";
+import YAML from "yaml";
 
 @customElement("ak-property-mapping-test-form")
 export class PolicyTestForm extends Form<PolicyTest> {
@@ -64,7 +65,7 @@ export class PolicyTestForm extends Form<PolicyTest> {
             <ak-form-element-horizontal
                 label=${t`Context`}
                 name="context">
-                <ak-codemirror mode="yaml">
+                <ak-codemirror mode="yaml" value=${YAML.stringify({})}>
                 </ak-codemirror>
             </ak-form-element-horizontal>
             ${this.result ? this.renderResult(): html``}