Expose file path in errors for dash-generate-components

Today, `dash-generate-components` can fail with confusing errors like:
```
ERROR: "__@iterator@3570" matches reserved word pattern: /^_.*$/

or

ERROR: "__html" matches reserved word pattern: /^_.*$/
```

and no context on where the failing component comes from.  We should surface the path to the failing component in the error message.