fix readln EOF handling

Cargo.lock

@@ -22,7 +22,7 @@ checksum = "b03f7fbd470aa8b3ad163c85cce8bccfc11cc9c44ef12da0a4eddd98bd307352"
 
 [[package]]
 name = "spl"
-version = "0.2.2"
+version = "0.2.3"
 dependencies = [
  "multicall",
  "once_cell",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "spl"
-version = "0.2.3"
+version = "0.2.4"
 edition = "2021"
 description = "Stack Pogramming Language: A simple, concise scripting language."
 license = "MIT"

src/std_fns.rs

@@ -663,9 +663,14 @@ pub fn import(stack: &mut Stack) -> OError {
 
 pub fn readln(stack: &mut Stack) -> OError {
     let mut s = String::new();
-    stdin()
+    if stdin()
         .read_line(&mut s)
-        .map_err(|x| stack.error(ErrorKind::IO(format!("{x:?}"))))?;
+        .map_err(|x| stack.error(ErrorKind::IO(format!("{x:?}"))))?
+        == 0
+    {
+        stack.push(Value::Null.spl());
+        return Ok(());
+    }
     let s = if let Some(s) = s.strip_suffix("\r\n") {
         s.to_owned()
     } else {