[OpenAPI] Improve missing query parameter error

src/HotChocolate/Adapters/src/Adapters.OpenApi.Core/Execution/DynamicEndpointMiddleware.cs

@@ -333,6 +333,12 @@ private static bool TryGetValueForParameter(
                     return false;
                 }
 
+                if (leaf.Type.IsNonNullType())
+                {
+                    throw new BadRequestException(
+                        $"Required route parameter '{leaf.ParameterKey}' is missing");
+                }
+
                 parameterValue = s_nullValueNode;
                 return true;
             }
@@ -357,6 +363,12 @@ private static bool TryGetValueForParameter(
                     return false;
                 }
 
+                if (leaf.Type.IsNonNullType())
+                {
+                    throw new BadRequestException(
+                        $"Required query parameter '{leaf.ParameterKey}' is missing");
+                }
+
                 parameterValue = s_nullValueNode;
                 return true;
             }

src/HotChocolate/Adapters/test/Adapters.OpenApi.Tests/Endpoints/HttpEndpointIntegrationTestBase.cs

@@ -84,6 +84,27 @@ public async Task Http_Get_With_Query_Parameter()
         response.MatchSnapshot();
     }
 
+    [Fact]
+    public async Task Http_Get_With_Missing_Required_Query_Parameter()
+    {
+        // arrange
+        var storage = new TestOpenApiDefinitionStorage(
+            """
+            query SearchProducts($text: String, $first: Int!)
+              @http(method: GET, route: "/products/search", queryParameters: ["text", "first"]) {
+              searchProductsPaginated(text: $text, first: $first)
+            }
+            """);
+        var server = CreateTestServer(storage);
+        var client = server.CreateClient();
+
+        // act
+        var response = await client.GetAsync("/products/search?text=Chair");
+
+        // assert
+        response.MatchSnapshot();
+    }
+
     [Fact]
     public async Task Http_Get_Without_Query_Parameter_That_Has_Default_Value()
     {

src/HotChocolate/Adapters/test/Adapters.OpenApi.Tests/Endpoints/__snapshots__/HttpEndpointIntegrationTestBase.Http_Get_With_Missing_Required_Query_Parameter.snap

@@ -0,0 +1,6 @@
+Headers:
+Content-Type: application/problem+json
+-------------------------->
+Status Code: BadRequest
+-------------------------->
+{"type":"https://tools.ietf.org/html/rfc9110#section-15.5.1","title":"Bad Request","status":400,"detail":"Required query parameter 'first' is missing"}

src/HotChocolate/Adapters/test/Adapters.OpenApi.Tests/TestSchema.cs

@@ -94,6 +94,9 @@ public string SearchProducts(string? text, float? minPrice)
             var formattedMinPrice = minPrice?.ToString(CultureInfo.InvariantCulture);
             return $"Searched for: {text ?? "all"}, minPrice: {formattedMinPrice}";
         }
+
+        public string SearchProductsPaginated(string? text, int first)
+            => $"Searched for: {text ?? "all"}, first: {first}";
     }
 
     public class Mutation