Error(s) in re-building vignettes:
  ...
duplicated vignette title:
  ‘Retrieving and Analyzing PubMed Records via easyPubMed’

--- re-building ‘easyPM_vignette_html.Rmd’ using rmarkdown
Warning in grep("\\\n$", msg) :
  input string 1 is invalid in this locale
Quitting from lines 39-50 (easyPM_vignette_html.Rmd) 
Error: processing vignette 'easyPM_vignette_html.Rmd' failed with diagnostics:
1: Input is not proper UTF-8, indicate encoding !
Bytes: 0xF0 0x93 0xFB 0xC1
2: error parsing attribute name
3: attributes construct error
4: Couldn't find end of Start Tag Ci<f0> line 844
5: PCDATA invalid Char value 16
6: Opening and ending tag mismatch: AbstractText line 1582 and MedlineCitation
7: Opening and ending tag mismatch: Abstract line 1581 and PubmedArticle
8: Opening and ending tag mismatch: Article line 1562 and PubmedArticleSet
9: Premature end of data in tag Citation line 1555
10: Premature end of data in tag Reference line 1554
11: Premature end of data in tag ReferenceList line 1295
12: Premature end of data in tag PubmedData line 1254
13: Premature end of data in tag PubmedArticle line 1106
14: Premature end of data in tag PubmedArticleSet line 3

--- failed re-building ‘easyPM_vignette_html.Rmd’

--- re-building ‘easyPM_vignette_pdf.Rmd’ using rmarkdown
Quitting from lines 39-50 (easyPM_vignette_pdf.Rmd) 
Error: processing vignette 'easyPM_vignette_pdf.Rmd' failed with diagnostics:
1: Input is not proper UTF-8, indicate encoding !
Bytes: 0xF0 0x23 0x14 0xFB
2: PCDATA invalid Char value 20
3: error parsing attribute name
4: attributes construct error
5: Couldn't find end of Start Tag Artic line 1514
6: Opening and ending tag mismatch: Reference line 1512 and ArticleIdList
7: Opening and ending tag mismatch: ReferenceList line 1295 and Reference
8: Opening and ending tag mismatch: Reference line 1517 and ArticleIdList
9: Opening and ending tag mismatch: PubmedData line 1254 and Reference
10: Opening and ending tag mismatch: PubmedArticle line 1106 and ReferenceList
11: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedData
12: Extra content at the end of the document

--- failed re-building ‘easyPM_vignette_pdf.Rmd’

SUMMARY: processing the following files failed:
  ‘easyPM_vignette_html.Rmd’ ‘easyPM_vignette_pdf.Rmd’

Error: Vignette re-building failed.
Error: Duplicate vignette titles.
  Ensure that the %\VignetteIndexEntry lines in the vignette sources
  correspond to the vignette titles.
Execution halted