Trying to output a Rmd in PDF - "incomplete final line found on..."

I was able to open .Rmd in html and word, but not pdf. I installed MikTex and I think I have whatever packages (if any) installed.

title: "Report on Gun Murders"
author: "paulgureghian"
date: "June 18, 2018"
output: pdf_document

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)

## Introduction 

This is a report on 2010 gun murder rates obtained from the FBI. 

We are going to use the following library:

```{r loading-libs, message=FALSE}

and load the data we already wrangled:


## Murder rate by state

We note the large stata to state variablity by generating a barplot showing the murder rate by state:

```{r murder-rate-by-state, echo=FALSE}
murders %>% mutate(abb = reorder(abb, rate)) %>%
    ggplot(aes(abb, rate)) +
    geom_bar(width = 0.5, stat = "identity", color = "black") +


this the error in the rmarkdown console:

incomplete final line found on 'Report_on_Gun_Murders.log'
Execution halted

the .log file seems to indicate that rstudio sees the miktex.