Setup errors

errors.go

@@ -1 +1,27 @@
 package main
+
+import "fmt"
+
+type ChecksumMissingError [32]byte
+type ChecksumInvalidError [32]byte
+type UnsubscribeRejectedError string
+type UnsubscribeUnexpectedError struct {
+	Message string
+	Code    int
+}
+
+func (e ChecksumMissingError) Error() string {
+	return fmt.Sprintf("checksum missing: %x", e)
+}
+
+func (e ChecksumInvalidError) Error() string {
+	return fmt.Sprintf("checksum invalid: %x", e)
+}
+
+func (e UnsubscribeRejectedError) Error() string {
+	return fmt.Sprintf("rejected: %s", string(e))
+}
+
+func (e UnsubscribeUnexpectedError) Error() string {
+	return fmt.Sprintf("unexpected error: %s", e.Message[:50])
+}