Fix mutation error mapping for multiple exception constructors

[michaelstaib]

Overview

• fix constructor-based payload error factory compilation for error types with multiple exception constructors
• correct the expression-chain fallback path to reuse the previous conditional expression directly
• add regression tests covering both constructor paths (InvalidOperationException and NullReferenceException)

Verification

• dotnet test src/HotChocolate/Core/test/Types.Mutations.Tests/HotChocolate.Types.Mutations.Tests.csproj --filter "FullyQualifiedName~ErrorMiddleware_Should_MapMultipleConstructors"
• dotnet test src/HotChocolate/Core/test/Types.Mutations.Tests/HotChocolate.Types.Mutations.Tests.csproj --filter "FullyQualifiedName~ErrorMiddlewareTests" --framework net10.0

Fixes #5991

[github-actions]

Fusion Gateway Performance Results

Simple Composite Query

	Req/s	Err%
Constant (50 VUs)	6921.55	0.00%
Ramping (0-500-0 VUs)	7379.40	0.00%

Response Times & Query

	Min	Med	Avg	P90	P95	Max
Constant	0.56ms	5.97ms	7.08ms	11.13ms	15.75ms	177.56ms
Ramping	0.56ms	24.29ms	29.82ms	64.16ms	77.05ms	183.78ms

query TestQuery {
  topProducts(first: 5) {
    inStock
    name
    price
    shippingEstimate
    upc
    weight
    reviews {
      id
      body
      author {
        id
        username
        name
      }
    }
  }
}

---

Deep Recursion Query

	Req/s	Err%
Constant (50 VUs)	1298.70	0.00%
Ramping (0-500-0 VUs)	1349.51	0.00%

Response Times & Query

	Min	Med	Avg	P90	P95	Max
Constant	4.06ms	33.97ms	37.39ms	51.13ms	60.41ms	344.28ms
Ramping	1.80ms	131.84ms	157.60ms	342.64ms	387.89ms	818.43ms

query TestQuery {
  users {
    id
    username
    name
    reviews {
      id
      body
      product {
        inStock
        name
        price
        shippingEstimate
        upc
        weight
        reviews {
          id
          body
          author {
            id
            username
            name
            reviews {
              id
              body
              product {
                inStock
                name
                price
                shippingEstimate
                upc
                weight
              }
            }
          }
        }
      }
    }
  }
  topProducts(first: 5) {
    inStock
    name
    price
    shippingEstimate
    upc
    weight
    reviews {
      id
      body
      author {
        id
        username
        name
        reviews {
          id
          body
          product {
            inStock
            name
            price
            shippingEstimate
            upc
            weight
          }
        }
      }
    }
  }
}

---

Variable Batching Throughput

	Req/s	Err%
Constant (50 VUs)	23696.38	0.00%
Ramping (0-500-0 VUs)	18302.93	0.00%

Response Times & Query

	Min	Med	Avg	P90	P95	Max
Constant	0.08ms	1.72ms	2.06ms	3.97ms	4.82ms	40.85ms
Ramping	0.08ms	9.52ms	11.52ms	23.78ms	28.43ms	104.18ms

query TestQuery($upc: ID!, $price: Long!, $weight: Long!) {
  productByUpc(upc: $upc) {
    inStock
    shippingEstimate(weight: $weight, price: $price)
  }
}

Variables (5 sets batched per request)

[
  { "upc": "1", "price": 899, "weight": 100 },
  { "upc": "2", "price": 1299, "weight": 1000 },
  { "upc": "3", "price": 15, "weight": 20 },
  { "upc": "4", "price": 499, "weight": 100 },
  { "upc": "5", "price": 1299, "weight": 1000 }
]

---

Run 22396202037 • Commit 5327570 • Wed, 25 Feb 2026 16:52:51 GMT