如何修复在r中编织时出现的“调用:库执行暂停”错误?

我只是试图将默认的Rmarkdonw代码(关于mtcars)编织成HTML(甚至PDF),但它不起作用。以下是Rmarkdown控制台中的完整错误消息:

Error in !character.only : invalid argument type
Calls: library
Execution halted

以下是knit中的默认代码:

---
title: "Untitled"
author: "Piyush Verma"
date: "December 19, 2017"
output: html_document
---

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

## R Markdown

This is an R Markdown document. Markdown is a simple formatting syntax for authoring HTML, PDF, and MS Word documents. For more details on using R Markdown see <http://rmarkdown.rstudio.com>.

When you click the **Knit** button a document will be generated that includes both contents as well as the output of any embedded R code chunks within the document. You can embed an R code chunk like this:

```{r cars}
summary(cars)
```

## Including Plots

You can also embed plots, for example:

```{r pressure, echo=FALSE}
plot(pressure)
```

Note that the `echo = FALSE` parameter was added to the code chunk to prevent printing of the R code that generated the plot.

我也尝试过做以下事情,但都没有成功:

1. Tools --&燃气轮机; Global options --&燃气轮机; Sweave --&燃气轮机; Weave RNW files using ...从…起 sweave 到 knitr
2. 在运行knit选项之前,重新安装rmarkdown和knitr并连接库

非常感谢您的建议。这是关于提交约翰·霍普金实用机器学习课程的最终项目集。