elixir-ls: fix elixir executable in path (#428066)

diff --git c/scripts/launch.sh w/scripts/launch.sh

index 21afbb1e..6b61f0b4 100755

index 21afbb1e..8bc5c382 100755

--- c/scripts/launch.sh

+++ w/scripts/launch.sh

@@ -1,125 +1,4 @@

 # In case that people want to tweak the path, which Elixir to use, or

 # whatever prior to launching the language server or the debug adapter, we

@@ -138,29 +17,18 @@ fi

@@ -138,29 +17,22 @@ fi

 # script so we can correctly configure the Erlang library path to

 # include the local .ez files, and then do what we were asked to do.

+ELX_STDLIB_PATH=${ELX_STDLIB_PATH:-@elixir@/lib/elixir}

+export ELX_STDLIB_PATH

+

+# ensure our elixir is in the path

+PATH="@elixir@/bin:$PATH"

+export PATH

+

+source "$SCRIPTPATH/exec.bash"