Fix bug in exception interceptor

Author: dsyer

spring-grpc-core/src/main/java/org/springframework/grpc/server/exception/GrpcExceptionHandlerInterceptor.java

@@ -64,16 +64,17 @@ public GrpcExceptionHandlerInterceptor(GrpcExceptionHandler exceptionHandler) {
 	public <ReqT, RespT> Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> call, Metadata headers,
 			ServerCallHandler<ReqT, RespT> next) {
 		Listener<ReqT> listener;
+		FallbackHandler handler = new FallbackHandler(this.exceptionHandler);
 		try {
 			listener = next.startCall(call, headers);
 		}
 		catch (Throwable t) {
-			call.close(this.exceptionHandler.handleException(t).getStatus(), headers(t));
+			call.close(handler.handleException(t).getStatus(), headers(t));
 			listener = new Listener<ReqT>() {
 			};
 			return listener;
 		}
-		return new ExceptionHandlerListener<>(listener, call, new FallbackHandler(this.exceptionHandler));
+		return new ExceptionHandlerListener<>(listener, call, handler);
 	}
 
 	private static Metadata headers(Throwable t) {

spring-grpc-core/src/test/java/org/springframework/grpc/server/exception/GrpcExceptionHandlerInterceptorTests.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2024-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.grpc.server.exception;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.grpc.server.exception.GrpcExceptionHandlerInterceptor.FallbackHandler;
+
+public class GrpcExceptionHandlerInterceptorTests {
+
+	@Test
+	void testNullStatusHandled() {
+		assertThat(new FallbackHandler(exception -> null).handleException(new RuntimeException("Test exception")))
+			.isNotNull();
+	}
+
+}