Add unsuccessfull response content logging

src/Digdir.Domain.Dialogporten.Infrastructure/HttpClientExtensions.cs

@@ -48,7 +48,8 @@ public static async Task<HttpResponseMessage> PostAsJsonEnsuredAsync(
             configureHeaders?.Invoke(httpRequestMessage.Headers);
             configureContentHeaders?.Invoke(httpRequestMessage.Content.Headers);
             var response = await client.SendAsync(httpRequestMessage, cancellationToken);
-            response.EnsureSuccessStatusCode();
+            await response.EnsureSuccessStatusCodeWithContent();
+
             return response;
         }
         catch (Exception e)

src/Digdir.Domain.Dialogporten.Infrastructure/HttpResponseMessageExtensions.cs

@@ -0,0 +1,35 @@
+namespace Digdir.Domain.Dialogporten.Infrastructure;
+
+public static class HttpResponseMessageExtensions
+{
+    private const int MaxContentLength = 1000;
+
+    public static async Task<HttpResponseMessage> EnsureSuccessStatusCodeWithContent(this HttpResponseMessage response)
+    {
+        if (response.IsSuccessStatusCode)
+        {
+            return response;
+        }
+
+        var content = await response.Content.ReadAsStringAsync();
+        if (string.IsNullOrWhiteSpace(content))
+        {
+            // This will throw HttpRequestException with the response status code and reason phrase
+            return response.EnsureSuccessStatusCode();
+        }
+
+        if (content.Length > MaxContentLength)
+        {
+            content = content[..MaxContentLength] + "[truncated after " + MaxContentLength + " characters]";
+        }
+
+        throw new HttpRequestException("Response unsuccessful (" + response.GetResponseCodeWithReasonPhrase() +
+                                       " with error content: " + content, null, response.StatusCode);
+
+    }
+
+    private static string GetResponseCodeWithReasonPhrase(this HttpResponseMessage response) =>
+        string.IsNullOrWhiteSpace(response.ReasonPhrase)
+            ? response.StatusCode.ToString()
+            : response.StatusCode + " " + response.ReasonPhrase;
+}