Electron Version: 7.1.1
Operating System: Windows 10 (1803)

If I set the 'margins' option when call webContents.print method,
The app will crash with no error message.

```js
let { remote } = require("electron");
let webContents = remote.getCurrentWebContents();
webContents.print(
  {
    margins: {
      marginType: "custom",
      top: 30,
      bottom: 0,
      left: 0,
      right: 0
    }
  },
  (success, errorType) => {
    if (!success) console.log(errorType);
  }
);
```

shell/browser/api/electron_api_web_contents.cc
content::RenderViewHost* new_host) {
  currently_committed_process_id_ = new_host->GetProcess()->GetID();
}
void Ws::RenderViewDeleted(content::RenderViewHost* render_view_host) {
  
  
  
  Emit("render-view-deleted", render_view_host->GetProcess()->GetID());
  if (-1 == currently_committed_process_id_ ||
      render_view_host->GetProcess()->GetID() ==
          currently_committed_process_id_) {
    currently_committed_process_id_ = -1;
    
    
    
    
    Emit("current-render-view-deleted",
         render_view_host->GetProcess()->GetID());
  }
}
void Ws::RenderProcessGone(base::TerminationStatus status) {