Replace invalid characters with UTF8 replacement char.

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 ### Changed
 - Properly close connection to server if ^C is pressed in interactive mode.
+- Replace invalid characters by UTF8 replacement char.
 
 ## [v0.6.1] 2023-07-25
 ### Changed

helpers.go

@@ -19,9 +19,9 @@ import (
 
 func validUTF8(s string) string {
 	// Remove invalid code points.
-	s = strings.ToValidUTF8(s, "")
+	s = strings.ToValidUTF8(s, "<EFBFBD>")
 	reg := regexp.MustCompile(`[\x{0000}-\x{0008}\x{000B}\x{000C}\x{000E}-\x{001F}]`)
-	s = reg.ReplaceAllString(s, "")
+	s = reg.ReplaceAllString(s, "<EFBFBD>")
 
 	return s
 }