error applying sample filter

```
Warning: Error in applyFilt.sampleFilter: samps_to_remove must contain at least one sample to remove
Stack trace (innermost first):
    70: applyFilt.sampleFilter
    69: pmartRseq::applyFilt
    68: observeEventHandler [/Users/brow015/devel/mead/server.R#317]
     1: shiny::runApp
```