Incorrect active_signature count when displaying signature help

[offsetcyan]

Describe the bug

ELP sends an incorrect active_signature count when displaying signature help.
According to helix-editor/helix#11269 it's an off-by-one error.

To Reproduce

Write a self-recursive function where the call has the same number of arguments as the function of that name that takes the most parameters, writing the arguments inside already-complete parentheses. A crash, at least in Helix, only occurs modifying the final argument to a function call when all other arguments are supplied.

i.e.

-module(test).

f(_) -> f(). % this is fine.
f(_) -> f(1). % adding in this 1 post-hoc will crash Helix because of this incorrect count.

Expected behavior

An correct active signature count is sent by elp.

Actual behavior

An incorrect active signature count is sent by elp.

Context

• ELP Version (output of elp version): elp 1.1.0+build-2024-07-16
• Editor used:

[offsetcyan]

Here is a helix.log output which shows communication with the LSP.