Fixed wrong index incrementing while parsing strings

CoreOSC.Tests/ParseTest.TestStringPadding.verified.txt

@@ -0,0 +1,16 @@
+{
+  Address: /test/strings,
+  Arguments: [
+    ,
+    1,
+    12,
+    123,
+    1234,
+    12345,
+    1234,
+    123,
+    12,
+    1,
+
+  ]
+}

CoreOSC.Tests/ParseTest.cs

@@ -73,4 +73,27 @@ public async Task TestNoAddress()
 
         await Verify(msg2);
     }
+
+    [Test]
+    public async Task TestStringPadding()
+    {
+        var msg = new OscMessage(
+            "/test/strings",
+            "",
+            "1",
+            "12",
+            "123",
+            "1234",
+            "12345",
+            "1234",
+            "123",
+            "12",
+            "1",
+            "");
+        var bytes = msg.GetBytes();
+
+        var msg2 = OscMessage.ParseMessage(bytes);
+
+        await Verify(msg2);
+    }
 }

CoreOSC/OscMessage.cs

@@ -217,9 +217,8 @@ public static OscMessage ParseMessage(Span<byte> msg)
                     break;
 
                 case 's':
-                    var stringVal = OscPacketUtils.GetString(msgReadOnlySpan, index);
+                    var stringVal = OscPacketUtils.GetString(msgReadOnlySpan, index, out index);
                     arguments.Add(stringVal);
-                    index += Encoding.UTF8.GetBytes(stringVal).Length;
                     break;
 
                 case 'b':
@@ -247,9 +246,8 @@ public static OscMessage ParseMessage(Span<byte> msg)
                     break;
 
                 case 'S':
-                    var symbolVal = OscPacketUtils.GetString(msgReadOnlySpan, index);
+                    var symbolVal = OscPacketUtils.GetString(msgReadOnlySpan, index, out index);
                     arguments.Add(new Symbol(symbolVal));
-                    index += symbolVal.Length;
                     break;
 
                 case 'c':

CoreOSC/OscPacketUtils.cs

@@ -39,12 +39,13 @@ public static int GetInt(ReadOnlySpan<byte> msg, int index) =>
 
     public static float GetFloat(Span<byte> msg, int index) => BitConverter.ToSingle(msg.ReverseSlice(index, 4));
 
-    public static string GetString(ReadOnlySpan<byte> msg, int index)
+    public static string GetString(ReadOnlySpan<byte> msg, int index, out int newIndex)
     {
         var i = index + 4;
         for (; i - 1 < msg.Length; i += 4)
         {
             if (msg[i - 1] != 0) continue;
+            newIndex = i;
             return Encoding.UTF8.GetString(msg[index..i]).Replace("\0", "");
         }