Don't crash on files without an extension

CHANGELOG.md

@@ -2,7 +2,8 @@
 
 ### Parsing
 
-Fixed a crash on parsing non-ASCII source files.
+Fixed a crash on parsing non-ASCII source files. Fixed a crash on
+files without an extension.
 
 Improved parsing for Rust punctuation.
 

src/main.rs

@@ -72,12 +72,10 @@ fn main() {
 
     let syntax_toml = ConfigDir::read_default_toml();
 
-    let extension = Path::new(&display_path)
-        .extension()
-        .and_then(OsStr::to_str)
-        .unwrap();
-
-    let lang = find_lang(syntax_toml, extension);
+    let lang = match Path::new(&display_path).extension() {
+        Some(extension) => find_lang(syntax_toml, &OsStr::to_string_lossy(extension)),
+        None => None,
+    };
 
     let terminal_width = match matches.value_of("COLUMNS") {
         Some(width) => width.parse::<usize>().unwrap(),