fix: add ConfigureAwait(false) throughout async code to prevent synchronization context deadlocks

CloudConvert.API/RestHelper.cs

@@ -22,12 +22,17 @@ internal RestHelper(HttpClient httpClient)
 
     internal async Task<T> RequestAsync<T>(HttpRequestMessage request, CancellationToken cancellationToken)
     {
-      var response = await _httpClient.SendAsync(request, cancellationToken);
-      var responseRaw = await response.Content.ReadAsStringAsync(cancellationToken);
+      var response = await _httpClient.SendAsync(request, cancellationToken).ConfigureAwait(false);
 
-      // Handle empty response body (e.g., HTTP 204 No Content)
-      // System.Text.Json throws when trying to deserialize an empty string
-      if (string.IsNullOrWhiteSpace(responseRaw) || response.StatusCode == System.Net.HttpStatusCode.NoContent)
+      // Short-circuit earlier as 204 will never have a body to read
+      if (response.StatusCode == System.Net.HttpStatusCode.NoContent)
+      {
+        return default;
+      }
+
+      var responseRaw = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+
+      if (string.IsNullOrWhiteSpace(responseRaw))
       {
         return default;
       }
@@ -37,8 +42,8 @@ internal async Task<T> RequestAsync<T>(HttpRequestMessage request, CancellationT
 
     internal async Task<string> RequestAsync(HttpRequestMessage request, CancellationToken cancellationToken)
     {
-      var response = await _httpClient.SendAsync(request, cancellationToken);
-      return await response.Content.ReadAsStringAsync(cancellationToken);
+      var response = await _httpClient.SendAsync(request, cancellationToken).ConfigureAwait(false);
+      return await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
     }
   }
 }

CloudConvert.API/WebApiHandler.cs

@@ -12,11 +12,12 @@ protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage
     {
       try
       {
-        var response = await base.SendAsync(request, cancellationToken);
+        var response = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
 
         if ((int)response.StatusCode >= 400)
         {
-          throw new WebApiException((await response.Content.ReadAsStringAsync(cancellationToken)).TrimLengthWithEllipsis(20000));
+          var errorBody = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+          throw new WebApiException(errorBody.TrimLengthWithEllipsis(20000));
         }
 
         return response;