Fix incorrect panic value when calling `ProjectionConfigurer.Delivery…

…Policy()` with a `nil` policy.

CHANGELOG.md

@@ -10,6 +10,13 @@ The format is based on [Keep a Changelog], and this project adheres to
 [keep a changelog]: https://keepachangelog.com/en/1.0.0/
 [semantic versioning]: https://semver.org/spec/v2.0.0.html
 
+## [Unreleased]
+
+### Fixed
+
+- Fixed incorrect panic value when calling
+  `ProjectionConfigurer.DeliveryPolicy()` with a `nil` policy.
+
 ## [0.13.0] - 2024-03-26
 
 - **[BC]** Updated to Dogma v0.13.0

projection_test.go

@@ -231,5 +231,16 @@ var _ = Describe("func FromProjection()", func() {
 				)
 			},
 		),
+		Entry(
+			"when the handler configures a nil delivery policy",
+			`delivery policy must not be nil`,
+			func(c dogma.ProjectionConfigurer) {
+				c.Identity("<name>", projectionKey)
+				c.Routes(
+					dogma.HandlesEvent[fixtures.MessageA](),
+				)
+				c.DeliveryPolicy(nil)
+			},
+		),
 	)
 })

projectionconfigurer.go

@@ -1,6 +1,9 @@
 package configkit
 
-import "github.com/dogmatiq/dogma"
+import (
+	"github.com/dogmatiq/configkit/internal/validation"
+	"github.com/dogmatiq/dogma"
+)
 
 type projectionConfigurer struct {
 	handlerConfigurer
@@ -15,7 +18,7 @@ func (c *projectionConfigurer) Routes(routes ...dogma.ProjectionRoute) {
 
 func (c *projectionConfigurer) DeliveryPolicy(p dogma.ProjectionDeliveryPolicy) {
 	if p == nil {
-		panic("delivery policy must not be nil")
+		validation.Panicf("delivery policy must not be nil")
 	}
 
 	c.deliveryPolicy = p