commitbot 0.6.0

diff --git a/src/parser.rs b/src/parser.rs
index abc1234..def5678 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -45,8 +45,12 @@ impl Parser {
     }
     pub fn parse(&mut self, input: &str) -> Result<Ast> {
-        let first_token = self.tokens.first().unwrap();
-        self.parse_expression(first_token)
+        let first_token = self.tokens.first()
+            .ok_or_else(|| ParseError::EmptyInput)?;
+        
+        self.parse_expression(first_token).map_err(|e| {
+            ParseError::InvalidSyntax { line: e.line, message: e.to_string() }
+        })
     }
 }