Handle empty buffer (#1)

* data/rawv2 tests: Typo less & format harder

* data/rawv2 tests: Panicking test for empty payload

* data/rawv2: Do not panic when given an empty buffer to parse

data/rawv2/rawv2.go

@@ -141,6 +141,9 @@ func Parse(d []byte) (*RuuviRawV2, error) {
 // ParseWithTime is as [Parse] except it permits passing an arbitrary timestamp
 // to be included in the returned struct.
 func ParseWithTime(d []byte, t time.Time) (*RuuviRawV2, error) {
+	if len(d) < 1 {
+		return nil, ErrorPacketTooSmall
+	}
 	minlen := 0
 	switch d[0] {
 	case data.VERSION_RAWV2:

data/rawv2/rawv2_test.go

@@ -201,7 +201,7 @@ func TestShort(t *testing.T) {
 	}
 }
 
-func TestBadVersio(t *testing.T) {
+func TestBadVersion(t *testing.T) {
 	vector := fmt.Sprintf("%02X", data.VERSION_RAWV1) + VECTOR_GOOD[2:]
 	raw := make([]byte, len(vector)/2)
 	n, _ := hex.Decode(raw, []byte(vector))
@@ -212,5 +212,11 @@ func TestBadVersio(t *testing.T) {
 	if !errors.Is(err, rawv2.ErrorPacketNotV2) {
 		t.Fatal(err)
 	}
+}
 
+func TestEmptyPayload(t *testing.T) {
+	_, err := rawv2.Parse(make([]byte, 0))
+	if !errors.Is(err, rawv2.ErrorPacketTooSmall) {
+		t.Fatal(err)
+	}
 }