Looks like your installation might be incomplete! Try the Verify Integrity of Game Files option, and see if the issue persists:
- Right-click Vermintide 2 in your Steam library sidebar
- Select ‘Properties’
- Select the ‘Local Files’ tab
- Select the ‘Verify the Integrity of Game Files’ button. This may take several minutes
- When complete, close and reopen Steam
- Launch Vermintide 2