Add KiwiStandardResponses method to create a "standard" 500 error

src/main/java/org/kiwiproject/jaxrs/KiwiStandardResponses.java

@@ -319,6 +319,28 @@ public static Response.ResponseBuilder standardNotFoundResponseBuilder(String er
         return standardErrorResponseBuilder(Response.Status.NOT_FOUND, errorDetails);
     }
 
+    /**
+     * Returns a 500 Internal Server Error response containing an {@link ErrorMessage} entity which uses
+     * {@code errorDetails} as the detailed error message.
+     *
+     * @param errorDetails the error message to use
+     * @return a 500 Internal Server Error response with {@code application/json} content type
+     */
+    public static Response standardInternalServerErrorResponse(String errorDetails) {
+        return standardInternalServerErrorResponseBuilder(errorDetails).build();
+    }
+
+    /**
+     * Returns a response builder with 500 Internal Server Error status and an {@link ErrorMessage} entity
+     * which uses {@code errorDetails} as the detailed error message.
+     *
+     * @param errorDetails the error message to use
+     * @return a response builder with a 500 status code and {@code application/json} content type
+     */
+    public static Response.ResponseBuilder standardInternalServerErrorResponseBuilder(String errorDetails) {
+        return standardErrorResponseBuilder(Response.Status.INTERNAL_SERVER_ERROR, errorDetails);
+    }
+
     /**
      * Returns a response having the given status and an {@link ErrorMessage} entity which uses {@code errorDetails}
      * as the detailed error message.

src/test/java/org/kiwiproject/jaxrs/KiwiStandardResponsesTest.java

@@ -271,6 +271,27 @@ void shouldReturnNotFoundResponse_WithErrorMessageEntity() {
         }
     }
 
+    @Nested
+    class StandardInternalServerErrorResponse {
+
+        @Test
+        void shouldReturnResponse_With500StatusAndErrorMessageEntity() {
+            var response = KiwiStandardResponses.standardInternalServerErrorResponse("This is the error message. It is very helpful.");
+
+            assertResponseEntityHasOneErrorMessage(response, 500, "This is the error message. It is very helpful.");
+            assertJsonResponseType(response);
+        }
+
+        @Test
+        void shouldReturnResponseBuilder_With500StatusAndErrorMessageEntity() {
+            var builder = KiwiStandardResponses.standardInternalServerErrorResponseBuilder("This is the error message. It is very helpful.");
+            var response = builder.build();
+
+            assertResponseEntityHasOneErrorMessage(response, 500, "This is the error message. It is very helpful.");
+            assertJsonResponseType(response);
+        }
+    }
+
     @Nested
     class StandardErrorResponse {