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

--- re-building ‘easyPM_vignette_html.Rmd’ using rmarkdown
Quitting from lines 39-50 (easyPM_vignette_html.Rmd) 
Error: processing vignette 'easyPM_vignette_html.Rmd' failed with diagnostics:
1: PCDATA invalid Char value 7
2: Opening and ending tag mismatch: ReferenceList line 740 and Reference
3: Opening and ending tag mismatch: PubmedData line 698 and ReferenceList
4: Opening and ending tag mismatch: PubmedArticle line 443 and PubmedData
5: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedArticle
6: Extra content at the end of the document

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

--- re-building ‘easyPM_vignette_pdf.Rmd’ using rmarkdown
Warning in for (i in seq_len(n)) { :
  closing unused connection 5 (https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=pubmed&WebEnv=NCID_1_101785679_130.14.22.32_9001_1546327853_543431859_0MetA0_S_MegaStore&query_key=1&retstart=0&retmax=500&rettype=null&retmode=xml)
Quitting from lines 39-50 (easyPM_vignette_pdf.Rmd) 
Error: processing vignette 'easyPM_vignette_pdf.Rmd' failed with diagnostics:
1: Opening and ending tag mismatch: Citation line 994 and AffiliationInfo
2: Opening and ending tag mismatch: Reference line 993 and Author
3: Opening and ending tag mismatch: Author line 1016 and ArticleId
4: Opening and ending tag mismatch: ReferenceList line 740 and ArticleIdList
5: Opening and ending tag mismatch: PubmedData line 698 and Reference
6: Opening and ending tag mismatch: PubmedArticle line 443 and ReferenceList
7: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedData
8: 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