Switch to using crossterm instead of termion in the REPL

This will allow for the REPL to be used on Windows, but has the side-effect of
making the REPL untestable via stdin, due to
crossterm-rs/crossterm#396

I haven't run into a failing test here in recent times except for occasionally
leaving in some debug output, which has been caught a few times. I'll add a
specific test for ensuring trace isn't left in later in the branch.

src/cli/Cargo.toml

@@ -25,8 +25,8 @@ koto_tempfile = { path = "../../libs/tempfile", version = "^0.8.0"}
 koto_toml = { path = "../../libs/toml", version = "^0.8.0"}
 koto_yaml = { path = "../../libs/yaml", version = "^0.8.0"}
 
+crossterm = "0.22.1" # A crossplatform terminal library for manipulating terminals.
 indexmap = "1.4.0"
-termion = "1.5.5"
 
 [dependencies.pulldown-cmark]
 # Markdown parsing

src/cli/src/main.rs

@@ -2,6 +2,7 @@ mod help;
 mod repl;
 
 use {
+    crossterm::tty::IsTty,
     koto::{bytecode::Chunk, Koto, KotoSettings},
     repl::{Repl, ReplSettings},
     std::{
@@ -137,8 +138,7 @@ fn run() -> Result<(), ()> {
                 Some(script),
             )
         }
-    } else if termion::is_tty(&stdin) || std::env::var_os("KOTO_FORCE_REPL_MODE").is_some() {
-        // Forcing REPL mode is useful for testing the behaviour of the REPL
+    } else if stdin.is_tty() {
         (None, None)
     } else {
         let mut script = String::new();
@@ -186,6 +186,8 @@ fn run() -> Result<(), ()> {
                 return Err(());
             }
         }
+
+        Ok(())
     } else {
         let mut repl = Repl::with_settings(
             ReplSettings {
@@ -194,8 +196,6 @@ fn run() -> Result<(), ()> {
             },
             koto_settings,
         );
-        repl.run();
+        repl.run().map_err(|_| ())
     }
-
-    Ok(())
 }