Align error representation of the institutions error

src/RobinTTY.NordigenApiClient.Tests/Endpoints/InstitutionsEndpointTests.cs

@@ -80,8 +80,8 @@ public async Task GetInstitutionsForNotCoveredCountry()
 
         Assert.Multiple(() =>
         {
-            Assert.That(response.Error!.Country.Detail, Is.EqualTo("US is not a valid choice."));
-            Assert.That(response.Error!.Country.Summary, Is.EqualTo("Invalid country choice."));
+            Assert.That(response.Error!.Detail, Is.EqualTo("US is not a valid choice."));
+            Assert.That(response.Error!.Summary, Is.EqualTo("Invalid country choice."));
         });
     }
 

src/RobinTTY.NordigenApiClient/JsonConverters/InstitutionsErrorConverter.cs

@@ -0,0 +1,18 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using RobinTTY.NordigenApiClient.Models.Errors;
+
+namespace RobinTTY.NordigenApiClient.JsonConverters;
+internal class InstitutionsErrorConverter : JsonConverter<InstitutionsError>
+{
+    public override InstitutionsError Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions? options)
+    {
+        var error = JsonSerializer.Deserialize<InstitutionsErrorInternal>(ref reader, options);
+        return new InstitutionsError(error!.Country);
+    }
+
+    public override void Write(Utf8JsonWriter writer, InstitutionsError value, JsonSerializerOptions options)
+    {
+        writer.WriteStringValue(value.ToString());
+    }
+}

src/RobinTTY.NordigenApiClient/Models/Errors/InstitutionsError.cs

@@ -5,20 +5,28 @@ namespace RobinTTY.NordigenApiClient.Models.Errors;
 /// <summary>
 /// An error description as returned by the institutions endpoint of the Nordigen API.
 /// </summary>
-public class InstitutionsError
+public class InstitutionsError : BasicError
 {
     /// <summary>
-    /// The error related to the requested institutions.
+    /// Creates a new instance of <see cref="InstitutionsError"/>.
     /// </summary>
+    /// <param name="country">The error related to the requested institutions.</param>
+    [JsonConstructor]
+    public InstitutionsError(BasicError country) : base(country.Summary, country.Detail) {}
+}
+
+/// <summary>
+/// Representation of the institutions error as returned by the Nordigen API.
+/// Since this representation doesn't add any useful information (only extra encapsulation)
+/// it is transformed to align this error with other errors returned by the API.
+/// </summary>
+internal class InstitutionsErrorInternal
+{
     [JsonPropertyName("country")]
     public BasicError Country { get; }
 
-    /// <summary>
-    /// Creates a new instance of <see cref="InstitutionsError"/>.
-    /// </summary>
-    /// <param name="country">The error related to the requested institutions.</param>
     [JsonConstructor]
-    public InstitutionsError(BasicError country)
+    public InstitutionsErrorInternal(BasicError country)
     {
         Country = country;
     }

src/RobinTTY.NordigenApiClient/NordigenClient.cs

@@ -63,7 +63,11 @@ public NordigenClient(HttpClient httpClient, NordigenClientCredentials credentia
         _httpClient = httpClient;
         _serializerOptions = new JsonSerializerOptions
         {
-            Converters = { new JsonWebTokenConverter(), new GuidConverter(), new CultureSpecificDecimalConverter() }
+            Converters = 
+            {
+                new JsonWebTokenConverter(), new GuidConverter(),
+                new CultureSpecificDecimalConverter(), new InstitutionsErrorConverter()
+            }
         };
 
         Credentials = credentials;
@@ -96,14 +100,14 @@ internal async Task<NordigenApiResponse<TResponse, TError>> MakeRequest<TRespons
             client = _httpClient;
         }
 
-        HttpResponseMessage ? response;
+        HttpResponseMessage? response;
         if (method == HttpMethod.Get)
             response = await client.GetAsync(requestUri, cancellationToken);
         else if (method == HttpMethod.Post)
             response = await client.PostAsync(requestUri, body, cancellationToken);
         else if (method == HttpMethod.Delete)
             response = await client.DeleteAsync(requestUri, cancellationToken);
-        else if(method == HttpMethod.Put)
+        else if (method == HttpMethod.Put)
             response = await client.PutAsync(requestUri, body, cancellationToken);
         else
             throw new NotImplementedException();