docs(angular): add missing non-null assertion operator (#2683)

Author: d-feliz

Diff for: docs/angular/your-first-app/5-adding-mobile.md

@@ -45,7 +45,7 @@ private async readAsBase64(photo: Photo) {
   }
   else {
     // Fetch the photo, read as a blob, then convert to base64 format
-    const response = await fetch(photo.webPath);
+    const response = await fetch(photo.webPath!);
     const blob = await response.blob();
 
     return await this.convertBlobToBase64(blob) as string;

Diff for: versioned_docs/version-v5/angular/your-first-app/5-adding-mobile.md

@@ -45,7 +45,7 @@ private async readAsBase64(photo: Photo) {
   }
   else {
     // Fetch the photo, read as a blob, then convert to base64 format
-    const response = await fetch(photo.webPath);
+    const response = await fetch(photo.webPath!);
     const blob = await response.blob();
 
     return await this.convertBlobToBase64(blob) as string;

Diff for: versioned_docs/version-v6/angular/your-first-app/5-adding-mobile.md

@@ -45,7 +45,7 @@ private async readAsBase64(photo: Photo) {
   }
   else {
     // Fetch the photo, read as a blob, then convert to base64 format
-    const response = await fetch(photo.webPath);
+    const response = await fetch(photo.webPath!);
     const blob = await response.blob();
 
     return await this.convertBlobToBase64(blob) as string;