Fixed a minor bug

src/parser/stage/groupify.rs

@@ -23,7 +23,10 @@ fn lookback_signs(
 				=> {
 					if o == "-" {
 						g.insert(i, Token::Operator(*l, String::from("neg")));
-					} else if o == "+" {
+					} else if o == "+" && g.len() != 0 {
+						// Don't remove "+" if it's the only token,
+						// this is a syntax error that is caught later.e
+
 						continue; // We should not increment i if we remove a token
 					} else {g.insert(i, a);}
 				},

src/parser/stage/treeify.rs

@@ -288,11 +288,16 @@ pub fn treeify(
 	context: &Context
 ) -> Result<Expression, (LineLocation, ParserError)> {
 
-	let g_inner: &mut VecDeque<Token> = match g {
-		Token::Group(_, ref mut x) => x,
+	let (l, g_inner): (LineLocation, &mut VecDeque<Token>) = match g {
+		Token::Group(l, ref mut x) => (l, x),
 		_ => panic!()
 	};
 
+	if g_inner.len() == 0 {
+		// This shouldn't ever happen.
+		return Err((l, ParserError::EmptyGroup));
+	}
+
 	let mut left_associative = true;
 	let mut j: i64 = 0;
 	while g_inner.len() > 1 {