Error(s) in re-building vignettes:
  ...
--- re-building 'Release.Rmd' using rmarkdown
[WARNING] This document format requires a nonempty <title> element.
  Defaulting to 'Release.knit' as the title.
  To specify a title, use 'title' in metadata or --metadata title="...".
--- finished re-building 'Release.Rmd'

--- re-building 'Use_case.Rmd' using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building 'Use_case.Rmd'

SUMMARY: processing the following file failed:
  'Use_case.Rmd'

Error: Vignette re-building failed.
Execution halted
Found the following files/directories:
  'Example'
Error(s) in re-building vignettes:
  ...
--- re-building ‘Release.Rmd’ using rmarkdown
[WARNING] This document format requires a nonempty <title> element.
  Defaulting to 'Release.knit' as the title.
  To specify a title, use 'title' in metadata or --metadata title="...".
--- finished re-building ‘Release.Rmd’

--- re-building ‘Use_case.Rmd’ using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette ‘Use_case.Rmd’ failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building ‘Use_case.Rmd’

SUMMARY: processing the following file failed:
  ‘Use_case.Rmd’

Error: Vignette re-building failed.
Execution halted
Found the following files/directories:
  ‘Example’
Error(s) in re-building vignettes:
--- re-building ‘Release.Rmd’ using rmarkdown
[WARNING] This document format requires a nonempty <title> element.
  Defaulting to 'Release.knit' as the title.
  To specify a title, use 'title' in metadata or --metadata title="...".
--- finished re-building ‘Release.Rmd’

--- re-building ‘Use_case.Rmd’ using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building ‘Use_case.Rmd’

SUMMARY: processing the following file failed:
  ‘Use_case.Rmd’

Error: Vignette re-building failed.
Execution halted
Found the following files/directories:
  ‘Example’
Error(s) in re-building vignettes:
--- re-building ‘Release.Rmd’ using rmarkdown
[WARNING] This document format requires a nonempty <title> element.
  Please specify either 'title' or 'pagetitle' in the metadata,
  e.g. by using --metadata pagetitle="..." on the command line.
  Falling back to 'Release.knit'
--- finished re-building ‘Release.Rmd’

--- re-building ‘Use_case.Rmd’ using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building ‘Use_case.Rmd’

SUMMARY: processing the following file failed:
  ‘Use_case.Rmd’

Error: Vignette re-building failed.
Execution halted
Found the following files/directories:
  ‘Example’
Error(s) in re-building vignettes:
--- re-building 'Release.Rmd' using rmarkdown
--- finished re-building 'Release.Rmd'

--- re-building 'Use_case.Rmd' using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building 'Use_case.Rmd'

SUMMARY: processing the following file failed:
  'Use_case.Rmd'

Error: Vignette re-building failed.
Execution halted
Error(s) in re-building vignettes:
--- re-building 'Release.Rmd' using rmarkdown
[WARNING] This document format requires a nonempty <title> element.
  Defaulting to 'Release.knit' as the title.
  To specify a title, use 'title' in metadata or --metadata title="...".
--- finished re-building 'Release.Rmd'

--- re-building 'Use_case.Rmd' using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building 'Use_case.Rmd'

SUMMARY: processing the following file failed:
  'Use_case.Rmd'

Error: Vignette re-building failed.
Execution halted
Error(s) in re-building vignettes:
  ...
--- re-building ‘Release.Rmd’ using rmarkdown
[WARNING] This document format requires a nonempty <title> element.
  Defaulting to 'Release.knit' as the title.
  To specify a title, use 'title' in metadata or --metadata title="...".
--- finished re-building ‘Release.Rmd’

--- re-building ‘Use_case.Rmd’ using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building ‘Use_case.Rmd’

SUMMARY: processing the following file failed:
  ‘Use_case.Rmd’

Error: Vignette re-building failed.
Execution halted
Found the following files/directories:
  ‘Example’
Found the following files/directories:
  ‘Example’
Error(s) in re-building vignettes:
  ...
--- re-building ‘Release.Rmd’ using rmarkdown
[WARNING] This document format requires a nonempty <title> element.
  Defaulting to 'Release.knit' as the title.
  To specify a title, use 'title' in metadata or --metadata title="...".
--- finished re-building ‘Release.Rmd’

--- re-building ‘Use_case.Rmd’ using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building ‘Use_case.Rmd’

SUMMARY: processing the following file failed:
  ‘Use_case.Rmd’

Error: Vignette re-building failed.
Execution halted
Found the following files/directories:
  ‘Example’
Error(s) in re-building vignettes:
--- re-building 'Release.Rmd' using rmarkdown
--- finished re-building 'Release.Rmd'

--- re-building 'Use_case.Rmd' using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building 'Use_case.Rmd'

SUMMARY: processing the following file failed:
  'Use_case.Rmd'

Error: Vignette re-building failed.
Execution halted
Error(s) in re-building vignettes:
--- re-building 'Release.Rmd' using rmarkdown
--- finished re-building 'Release.Rmd'

--- re-building 'Use_case.Rmd' using rmarkdown
Warning: Removed 16 rows containing missing values (geom_point).
Warning: Removed 16 rows containing missing values (geom_point).
Quitting from lines 142-147 (Use_case.Rmd) 
Error: processing vignette 'Use_case.Rmd' failed with diagnostics:
attempt to use zero-length variable name
--- failed re-building 'Use_case.Rmd'

SUMMARY: processing the following file failed:
  'Use_case.Rmd'

Error: Vignette re-building failed.
Execution halted