vim.fn["vimtex#env#is_inside"]("document") not working when working on an \include-ed files that lack a \begin{document}

[de-mirage2]

Description

After writing into the main-file \include{eras/period1} to include a sub-file period1.tex stored in /eras/, VimTeX doesn't recognize how typing into the sub-file eras/period1.tex works as a document, and that the sub-file doesn't require \begin{document} nor \end{document}.

As such, my LuaSnip snippets which depend on vim.fn["vimtex#env#is_inside"]("document") don't show up when editing eras/period1, since it can't find the \begin{document}.

Steps to reproduce

1. Create a basic document in main.tex that has an include statement i.e. \include{subfolder/chapter1}
2. Create a folder in the same directory i.e. subfolder
3. Within the directory create a new file i.e. chapter1.tex
4. Evaluate vim.fn"vimtex#env#is_inside" in any way possible - I used LuaSnip snippets to verify

Expected behavior

for vim.fn"vimtex#env#is_inside" to be evaluated as true and my snippets seen

Actual behavior

this doesn't happen

Do you use a latexmkrc file?

No

VimtexInfo

Sub-file:

System info:
  OS: Linux 6.8.2-arch2-1
  Vim version: NVIM v0.10.2
  Has clientserver: true
  Servername: /run/user/1000/nvim.1001420.0

VimTeX project: period4
  base: period4.tex
  root: /home/de_mirage/Classwork/HS/11th/USH/Notes/Period4
  tex: /home/de_mirage/Classwork/HS/11th/USH/Notes/Period4/period4.tex
  main parser: fallback current file
  document class: 
  compiler: latexmk
    engine: -pdf
    options:
      -verbose
      -file-line-error
      -synctex=1
      -interaction=nonstopmode
    callback: 1
    continuous: 1
    executable: latexmk
  viewer: Zathura
    xwin id: 0
  qf method: LaTeX logfile

Main-file:
System info:
  OS: Linux 6.8.2-arch2-1
  Vim version: NVIM v0.10.2
  Has clientserver: true
  Servername: /run/user/1000/nvim.1005373.0

VimTeX project: APUSH_FN
  base: APUSH_FN.tex
  root: /home/de_mirage/Classwork/HS/11th/USH/Notes
  tex: /home/de_mirage/Classwork/HS/11th/USH/Notes/APUSH_FN.tex
  main parser: current file verified
  document class: memoir
  packages: array booktabs dcolumn delarray epstopdf-base etoolbox expl3 geometry gettitlestring graphics graphicx iftex ifvtex infwarerr keyval kvoptions kvsetkeys ltxcmds nameref pgf pgfcomp-version-0-65 pgfcomp-version-1-18 pgfcore pgffor pgfkeys pgfmath pgfrcs pgfsys refcount shortvrb tabularx textcase tikz trig verbatim xcolor xparse xpatch
  source files:
    APUSH_FN.tex
    Period4/period4.tex
  compiler: latexmk
    engine: -pdf
    options:
      -verbose
      -file-line-error
      -synctex=1
      -interaction=nonstopmode
    callback: 1
    continuous: 1
    executable: latexmk
  viewer: Zathura
    xwin id: 0
  qf method: LaTeX logfile