Fix single line comment bug

Comments which were on the last line of an SQL query would cause the scanner to never reach the end of the reader stream, hangining indefinitely.

This fix ensures that the single line comment is ended when an EOF is reached.

sql/scanner.go

@@ -300,7 +300,9 @@ func (s *scanner) scanCommentSingle(chp ...rune) (tok Token, lit string, val int
 
 	// Read subsequent characters
 	for {
-		if ch := s.next(); ch == '\n' || ch == '\r' {
+		if ch := s.next(); ch == eof {
+			break
+		} else if ch == '\n' || ch == '\r' {
 			buf.WriteRune(ch)
 			break
 		} else {