When I integrated this How to use the standard - (hyphen) as the hyp{} command from the hyphenat package? into my main document, I got errors about hyphen usage on translations packages:

Redoing nameref's sectioning

Redoing nameref's label

(D:UserDocumentslatextexmfsinstalltexlatexmicrotypemt-cmr.cfg) (D:UserDocumentslatextexmfsinstalltexcontextbasesupp-pdf.mkii

[Loading MPS to PDF converter (version 2006.09.02).]

) ABD: EverySelectfont initializing macros (D:UserDocumentslatextexmfsinstalltexlatexbeamertranslatordictstranslator-basic-dictionarytranslator-basic-dictionary-English.dict

D:UserDocumentslatextexmfsinstalltexlatexbeamertranslatordictstranslator-basic-dictionarytranslator-basic-dictionary-English.dict:2: Missing endcsname inserted

D:UserDocumentslatextexmfsinstalltexlatexbeamertranslatordictstranslator-basic-dictionarytranslator-basic-dictionary-English.dict:2:  ==> Fatal error occurred, no output PDF file produced!

Transcript written on D:thesissetupcachemain.log.

gross execution time: 8855 ms

user mode: 8625 ms, kernel mode: 125 ms, total: 8750



... on main.log

Package lastpage Info: Please have a look at the pageslts package at

(lastpage)             https://www.ctan.org/pkg/pageslts

(lastpage)             ! on input line 332.

c@lstlisting=count631

 (D:UserDocumentslatextexmfsinstalltexlatexbeamertranslatordictstranslator-basic-dictionarytranslator-basic-dictionary-English.dict

Dictionary: translator-basic-dictionary, Language: English 



D:UserDocumentslatextexmfsinstalltexlatexbeamertranslatordictstranslator-basic-dictionarytranslator-basic-dictionary-English.dict:2: Missing endcsname inserted 

Here is how much of TeX's memory you used:

Then, I included it like this in my document:

begin{document}



    ExplSyntaxOn

    cs_new:Npn hyphenfix_emdash:c {---}

    ...



    Tests.



    Encoding-encoding-encoding-encoding-encoding-encoding-encoding-encoding-encoding-encoding.



end{document}

And it worked!

Is there a way to include it on my preamble instead of the start of my document?

Update

As suggested on comment, I added AtBeginDocument{, but it did not work:

usepackage{expl3}

AtBeginDocument{%

    ExplSyntaxOn

    cs_new:Npn hyphenfix_emdash:c {---}

    cs_new:Npn hyphenfix_endash:c {--}



    cs_new:Npn hyphenfix_discardnext:NN #1#2{#1}





    catcode`-=active



    cs_new_protected:Npn -{

        futurelethyphenfix_nexttokhyphenfix_i:w

    }



    cs_new:Npn hyphenfix_i:w {

        cs_if_eq:NNTF{hyphenfix_nexttok}{-}{

            %discard the next `-` token

            hyphenfix_discardnext:NN{futurelethyphenfix_nexttokhyphenfix_ii:w}

        }{

            % from package hyphenat

            hyp

        }

    }



    cs_new:Npn hyphenfix_ii:w {

        cs_if_eq:NNTF{hyphenfix_nexttok}{-}{

            hyphenfix_discardnext:NN{hyphenfix_emdash:c}

        }{

            hyphenfix_endash:c

        }

    }

    ExplSyntaxOff

}

Not throw another error:

Package microtype Info: Loading generic protrusion settings for font family

(microtype)             `pcr' (encoding: T1).

(microtype)             For optimal results, create family-specific settings.

(microtype)             See the microtype manual for details.

main.tex:333: Missing $ inserted 

Here is how much of TeX's memory you used:

On the line main.tex:333 I have begin{document}.