Off the top of my head, is this behavior happening because when the html is being parsed/interpolated by thePhoenix heex engine, it is treating <!— —> like an html tag? Is that how html interprets the comment in general?
Then the interpolation would throw an error as it seems to be doing.
In which case, do we just need to add something to identify the comment tag syntax? Or is it something else or much more complex? 
The parser identifies <!-- as a comment in handle_text, and passes it off to handle_comment, which needs to find a closing --> or it will raise. The problem is that it seems to “give up” on the search as soon as it hits a <%
Here is the solution I came up with:
lib/myapp_web directory and define a new module in it:defmodule HeexIgnore do
use Phoenix.Component
def ignore(assigns), do: ~H""
end
lib/myapp_web.ex find the private function defp view_helpers do... which contains several import statements. Add this line as one of the imports in that function:import HeexIgnore
<.ignore> ... </.ignore> incantation in order to completely ignore large chunks of lines.Thanks to @chrismccord for giving me some tips in the GitHub issue referenced by @kokolegorille
I started reading the issue around this that everyone’s been having a conversation on, and not sure I have much else to add. Seems very intentional that they have currently chose this implementation around the comments and sounds like there are some workarounds if you need a different behavior until they can revisit this again and discuss more scenarios.
Thanks for the links! 
Edit: Yes, looks like @tadasajon went with one of those workarounds.
for the record:
this is solved with <%!-- --%> since elixir v1.14.0 09/2022:
<%!-- comment
over
multiple lines --%>
https://github.com/elixir-lang/elixir/pull/11505
getting it to work in vscode:
vscode-elixir-ls supports it since 0.12.0:
https://github.com/elixir-lsp/vscode-elixir-ls/commit/9afc4d21eb7ed870f296e3d2fd34ef95cd4d16ea
i just had to add this to my settings.json to use it in vscode with the default comment-shortcut:
"custom-language-properties": {
"phoenix-heex.comments.blockComment": ["<%!--", "--%>"]
},
(phoenix-heex. might be named html-eex. or similar in your setup)