Don't panic on unknown syntax

src/easy.rs

@@ -97,8 +97,8 @@ impl<'a> HighlightFile<'a> {
         let extension = path.extension().and_then(|x| x.to_str()).unwrap_or("");
         let f = try!(File::open(path));
         let reader = BufReader::new(f);
-        // TODO use first line detection and don't panic
-        let syntax = ss.find_syntax_by_extension(extension).unwrap();
+        // TODO use first line detection
+        let syntax = ss.find_syntax_by_extension(extension).unwrap_or_else(|| ss.find_syntax_plain_text());
         Ok(HighlightFile {
             reader: reader,
             highlight_lines: HighlightLines::new(syntax, theme),

src/parsing/syntax_set.rs

@@ -119,6 +119,9 @@ impl SyntaxSet {
     /// Good as a fallback when you can't find another syntax but you still want
     /// to use the same highlighting pipeline code.
     ///
+    /// This syntax should always be present, if not this method will panic.
+    /// If the way you load syntaxes doesn't create one, use `load_plain_text_syntax`.
+    ///
     /// # Examples
     /// ```
     /// use syntect::parsing::SyntaxSet;