Add more details on lsif upload failure

I'm guessing this could be an endpoint access error but I can't really dig too much into this since the error is fairly obtuse. A `-verbose` option could be helpful here!

```
jwon@jwon-dbx:~/src/server$ src lsif upload
Inferred arguments:
  -repo=<removed>
  -commit=<removed>
  -root=
  -file=./dump.lsif
  -indexer=lsif-go

invalid character '<' looking for beginning of value
```