fix json parsing error on upload

Unexpected character encountered while parsing value: �. Path '', line 0, position 0.
at Sleet.JsonUtility.<LoadJsonAsync>d__13.MoveNext() in Sleet\src\SleetLib\Utility\JsonUtility.cs:line 181

Author: mfkl

src/SleetLib/FileSystem/AmazonS3File.cs

@@ -115,6 +115,14 @@ protected override async Task CopyToSource(ILogger log, CancellationToken token)
                 {
                     contentType = "image/svg+xml";
                 }
+                else if (absoluteUri.AbsoluteUri.EndsWith("/icon"))
+                {
+                    contentType = "image/png";
+                }
+                else if (absoluteUri.AbsoluteUri.EndsWith("/readme"))
+                {
+                    contentType = "text/markdown";
+                }
                 else if (key.EndsWith(".json", StringComparison.Ordinal)
                          || await JsonUtility.IsJsonAsync(LocalCacheFile.FullName))
                 {
@@ -131,14 +139,6 @@ protected override async Task CopyToSource(ILogger log, CancellationToken token)
                 {
                     contentType = "application/octet-stream";
                 }
-                else if (absoluteUri.AbsoluteUri.EndsWith("/icon"))
-                {
-                    contentType = "image/png";
-                }
-                else if (absoluteUri.AbsoluteUri.EndsWith("/readme"))
-                {
-                    contentType = "text/markdown";
-                }
                 else
                 {
                     log.LogWarning($"Unknown file type: {absoluteUri}");