add error for unknown chars

read/read.go

@@ -1,6 +1,7 @@
 package read
 
 import (
+	"fmt"
 	"mal-go/hash_map"
 	"mal-go/symbol"
 	"mal-go/vector"
@@ -47,6 +48,8 @@ func readForm(s string, pos int, ns string) (any, any, int) {
 			res, err, pos = readVector(s, pos, ns)
 		case '(':
 			res, err, pos = readList(s, pos, ns)
+		default:
+			return nil, "unexpected char: '" + fmt.Sprint(c) + "'", pos
 		}
 	}
 	return res, err, pos