title: Graphics are creating an error when I attempt to knit in R Markdown
body: <p>I am attempting to knit a pdf document using R-Markdown. It appears the issue I'm having is directly related to me trying to put histograms in my paper. I attempted to knit the document without the histograms and it rendered fine, but once I added the histogram code I keep on getting the following error:</p>
  
  <pre><code>output file: Final_Version_1_-_Assignment_1_-_STA304.knit.md
  
  ! LaTeX Error: File `Final_Version_1_-_Assignment_1_-_STA304_files/figure-latex
  /Q2_part_a_call' not found.
  
  Error: Failed to compile Final_Version_1_-_Assignment_1_-_STA304.tex. See https://yihui.name/tinytex/r/#debugging for debugging tips. See Final_Version_1_-_Assignment_1_-_STA304.log for more info.
  Execution halted
  </code></pre>
  
  <p>For reference here is the R-Markdown Code:</p>
  
  <pre><code>---
  title: "Stats - Assignment 1"
  author: "John Doe"
  date: "September 26, 2019"
  output:
    pdf_document: default
    html_document: default
  ---
  
  
  ``{r setup, include=TRUE}
  knitr::opts_chunk$set(echo = TRUE)
  
  library(tidyverse)
  
  pop = c(1,0,0,4,1,6,6,3,5,3,1)
  population = data.frame(pop)
  
  ``
  Question 2) a) The following is a histogram of the population data:
  
  ``{r Q2_part_a_code, include = FALSE}
  #Assignment 1 - Q2 - part a) 
  
  #Please enter the data frame being used and the column to be analyzed. Both without quotation marks.
  
    population_histogram = function(df_for_use,column_to_analyze){
  
    pop_histo = ggplot(data = df_for_use) + geom_histogram(mapping = aes(x = column_to_analyze), binwidth = 0.5)
  
  
    print(pop_histo)
  
      }
  ``
  
  
  ``{r Q2_part_a_call), include = TRUE}
  population_histogram(population,pop)
  ``
  
  </code></pre>
  
  <p>Note: I just put double ticks here so the code chunk wouldn't clash with the markdown on this page. I'm aware it is three ticks for functions.</p>
  
  <p>The code works fine if I just execute from within the R-Markdown window, but once I try to knit a pdf I get the above error. </p>
  
  <p><strong>*EDIT:</strong>  After more playing around it is definitely an issue with the histogram. When I tried to knit an MS Word document it decided to skip the histogram. It did successfully knit the whole document as html.</p>