[DURACOM-240] Improve markdown pipe in order to check for empty values

src/app/shared/utils/markdown.pipe.spec.ts

@@ -55,6 +55,20 @@ describe('Markdown Pipe', () => {
     );
   });
 
+  it('should render undefined value', async () => {
+    await testTransform(
+      undefined,
+      undefined,
+    );
+  });
+
+  it('should render null value', async () => {
+    await testTransform(
+      null,
+      null,
+    );
+  });
+
   async function testTransform(input: string, output: string) {
     expect(
       await markdownPipe.transform(input),

src/app/shared/utils/markdown.pipe.ts

@@ -11,6 +11,7 @@ import {
 } from '@angular/platform-browser';
 
 import { environment } from '../../../environments/environment';
+import { isEmpty } from '../empty.util';
 
 const markdownItLoader = async () => (await import('markdown-it')).default;
 type LazyMarkdownIt = ReturnType<typeof markdownItLoader>;
@@ -60,8 +61,8 @@ export class MarkdownPipe implements PipeTransform {
   ) {
   }
 
-  async transform(value: string): Promise<SafeHtml> {
-    if (!environment.markdown.enabled) {
+  async transform(value: string, forcePreview = false): Promise<SafeHtml> {
+    if (isEmpty(value) || (!environment.markdown.enabled && !forcePreview)) {
       return value;
     }
     const MarkdownIt = await this.markdownIt;