Fix code quality report display

Changelog: fixed

app/assets/javascripts/reports/codequality_report/components/codequality_issue_body.vue

@@ -34,7 +34,7 @@ export default {
       return `${this.severityLabel} - ${this.issue.name}`;
     },
     issueSeverity() {
-      return this.issue.severity.toLowerCase();
+      return this.issue.severity?.toLowerCase();
     },
     isStatusSuccess() {
       return this.status === STATUS_SUCCESS;

spec/frontend/reports/codequality_report/components/codequality_issue_body_spec.js

@@ -51,6 +51,7 @@ describe('code quality issue body issue body', () => {
       ${'blocker'}  | ${'text-danger-800'}    | ${'severity-critical'}
       ${'unknown'}  | ${'text-secondary-400'} | ${'severity-unknown'}
       ${'invalid'}  | ${'text-secondary-400'} | ${'severity-unknown'}
+      ${undefined}  | ${'text-secondary-400'} | ${'severity-unknown'}
     `(
       'renders correct icon for "$severity" severity rating',
       ({ severity, iconClass, iconName }) => {