ident: decode twitch vod name

There are a few unknown fields, represented as is for now.

Signed-off-by: Yonah <contrib@gensokyo.uk>

streamdata_test.go

@@ -0,0 +1,31 @@
+package streamdata_test
+
+import (
+	"testing"
+
+	"git.gensokyo.uk/yonah/streamdata"
+)
+
+func TestErrors(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name string
+		err  error
+		want string
+	}{
+		{"IdentFieldError", streamdata.IdentFieldError(0xcafe),
+			"got 51966 field(s) instead of 7"},
+		{"IdentFFError", &streamdata.IdentFFError{Got: 0xcafe, Want: 0xbabe},
+			"got 51966 bytes for a 47806-byte long free-form field"},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			if got := tc.err.Error(); got != tc.want {
+				t.Errorf("Error: %q, want %q", got, tc.want)
+			}
+		})
+	}
+}