actually throw error on bad dialogue

src/dialogue.rs

@@ -12,11 +12,19 @@ pub struct Dialogue {
 impl Dialogue {
     pub fn from_str(str: &str) -> Result<Dialogue, crate::Error> {
         let mut lines: Vec<&str> = str.lines().collect();
+
+        if lines.is_empty() || !lines[0].starts_with("DLG ") {
+            return Err(crate::Error::Dialogue);
+        }
+
         let id = lines[0].replace("DLG ", "");
 
-        let name = if lines.last().unwrap().starts_with("NAME ") {
-            Some(lines.pop().unwrap().replace("NAME ", ""))
+        let last_line = lines.pop().unwrap();
+
+        let name = if last_line.starts_with("NAME ") {
+            Some(last_line.replace("NAME ", ""))
         } else {
+            lines.push(last_line);
             None
         };