listfiles
documentclass{article}
usepackage{etoc}

begin{document}
tableofcontents‎‎
end{document}

This is pdfTeX, Version 3.14159265-2.6-1.40.19 (TeX Live 2018) (preloaded format=pdflatex)
 restricted write18 enabled.
entering extended mode
(./mwe.tex
LaTeX2e <2018-04-01> patch level 4
(/usr/local/texlive/2018/texmf-dist/tex/latex/base/article.cls
Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
(/usr/local/texlive/2018/texmf-dist/tex/latex/base/size10.clo))
(/usr/local/texlive/2018/texmf-dist/tex/latex/etoc/etoc.sty
(/usr/local/texlive/2018/texmf-dist/tex/latex/tools/multicol.sty)) (./mwe.aux)

! Package inputenc Error: Unicode character ‎ (U+200E)
(inputenc)                not set up for use with LaTeX.

See the inputenc package documentation for explanation.
Type  H <return>  for immediate help.
 ...

l.6 tableofcontents‎
                       ‎
? R
OK, entering nonstopmode...

! Package inputenc Error: Unicode character ‎ (U+200E)
(inputenc)                not set up for use with LaTeX.

See the inputenc package documentation for explanation.
Type  H <return>  for immediate help.
 ...

l.6 tableofcontents‎‎

[1{/usr/local/texlive/2018/texmf-var/fonts/map/pdftex/updmap/pdftex.map}]
(./mwe.aux)

 *File List*
 article.cls    2014/09/29 v1.4h Standard LaTeX document class
  size10.clo    2014/09/29 v1.4h Standard LaTeX file (size option)
    etoc.sty    2018/02/23 v1.08n Completely customisable TOCs (JFB)
multicol.sty    2018/04/20 v1.8s multicolumn formatting (FMi)
 ***********

 )
(see the transcript file for additional information)</usr/local/texlive/2018/te
xmf-dist/fonts/type1/public/amsfonts/cm/cmbx12.pfb></usr/local/texlive/2018/tex
mf-dist/fonts/type1/public/amsfonts/cm/cmr10.pfb>
Output written on mwe.pdf (1 page, 16281 bytes).
SyncTeX written on mwe.synctex.gz.
Transcript written on mwe.log.

documentclass{article}
%usepackage{etoc}
DeclareUnicodeCharacter{200E}{HALLO}
begin{document}
tableofcontents‎‎
end{document}