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: Input is not proper UTF-8, indicate encoding !
Bytes: 0xBB 0x10 0x08 0x0A
2: PCDATA invalid Char value 16
3: PCDATA invalid Char value 8
4: Opening and ending tag mismatch: ArticleId line 792 and Reference
5: Opening and ending tag mismatch: Citation line 822 and Reference
6: expected '>'
7: Opening and ending tag mismatch: ArticleIdList line 791 and PubmedData
8: Opening and ending tag mismatch: Reference line 789 and PubmedArticle
9: expected '>'
10: Opening and ending tag mismatch: AffiliationInfo line 1143 and Author
11: expected '>'
12: Opening and ending tag mismatch: AuthorList line 1127 and Article
13: Opening and ending tag mismatch: Article line 1104 and MedlineCitation
14: Unescaped '<' not allowed in attributes values
15: attributes construct error
16: Couldn't find end of Start Tag ArticleId line 1511
17: Opening and ending tag mismatch: ArticleIdList line 1510 and Citation
18: Opening and ending tag mismatch: MedlineCitation line 1097 and PubmedArticle
19: Unescaped '<' not allowed in attributes values
20: attributes construct error
21: Couldn't find end of Start Tag ArticleId line 2579
22: Opening and ending tag mismatch: ArticleIdList line 2578 and Reference
23: expected '>'
24: Opening and ending tag mismatch: ReferenceList line 2569 and PubmedData
25: Opening and ending tag mismatch: PubmedData line 2522 and PubmedArticle
26: StartTag: invalid element name
27: Opening and ending tag mismatch: ReferenceList line 3672 and Reference
28: Opening and ending tag mismatch: PubmedData line 3641 and ReferenceList
29: Opening and ending tag mismatch: PubmedArticle line 3381 and PubmedData
30: expected '>'
31: Premature end of data in tag ReferenceList line 740
32: Premature end of data in tag PubmedData line 698
33: Premature end of data in tag PubmedArticle line 443
34: Premature end of data in tag PubmedArticleSet line 3

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

--- re-building ‘easyPM_vignette_pdf.Rmd’ using rmarkdown
Warning in for (j in seq_along(x)) { :
  closing unused connection 5 (https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=pubmed&WebEnv=NCID_1_109933947_130.14.22.215_9001_1546457757_801278566_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: expected '>'
2: Opening and ending tag mismatch: Reference line 999 and Refe
3: PCDATA invalid Char value 8
4: Opening and ending tag mismatch: ReferenceList line 740 and AffiliationInfo
5: Opening and ending tag mismatch: PubmedData line 698 and Author
6: Specification mandate value for attribute Va
7: attributes construct error
8: Couldn't find end of Start Tag Author line 1026
9: Opening and ending tag mismatch: PubmedArticle line 443 and Reference
10: Opening and ending tag mismatch: PubmedArticleSet line 3 and ReferenceList
11: 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