Fix bug where `:h` would leave pending keys

Using `:h` with a key that branches into other bindings, such as `g` or
`z` would leave the inputted keys as pending, meaning that any following
keypresses would register as if the looked-up keys had been typed first.

helix-term/src/commands/typed.rs

@@ -2490,9 +2490,13 @@ fn help(cx: &mut compositor::Context, args: &[Cow<str>], event: PromptEvent) ->
                             KeymapResult::NotFound | KeymapResult::Cancelled(_) => {
                                 Err(anyhow!("No command found for '{}'", arg))
                             }
-                            KeymapResult::Pending(_) => Err(anyhow!(
-                                "`:help` for branching keybinds is not yet supported."
-                            )),
+                            KeymapResult::Pending(_) => {
+                                // Clear pending keys
+                                keymaps.get(mode, crate::keymap::macros::key!(Esc));
+                                Err(anyhow!(
+                                    "`:help` for branching keybinds is not yet supported."
+                                ))
+                            }
                             KeymapResult::MatchedSequence(_) => Err(anyhow!(
                                 "`:help` for sequence bindings is not yet supported."
                             )),