Handle early GraphQLExceptions in ExecutionGraphQlService

Prior to this commit, the `ExecutionGraphQlService` would throw
`GrahphQLException` instances if errors happen early in the process, for
example in some cases of document parsing/validation.

Such exception would be thrown directly and not reflected in the GraphQL
response if those are `GraphQLError`.

This commit ensures that a fallback GraphQL response is created in this
case and that it contains the relevant `GraphQLError` information.

Fixes gh-1118

spring-graphql/src/main/java/org/springframework/graphql/execution/DefaultExecutionGraphQlService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -22,8 +22,11 @@ import java.util.List;
 import java.util.function.BiFunction;
 
 import graphql.ExecutionInput;
+import graphql.ExecutionResult;
 import graphql.GraphQL;
 import graphql.GraphQLContext;
+import graphql.GraphQLError;
+import graphql.GraphQLException;
 import graphql.execution.ExecutionIdProvider;
 import graphql.execution.instrumentation.dataloader.EmptyDataLoaderRegistryInstance;
 import io.micrometer.context.ContextSnapshotFactory;
@@ -102,6 +105,12 @@ public class DefaultExecutionGraphQlService implements ExecutionGraphQlService {
 			ExecutionInput executionInputToUse = registerDataLoaders(executionInput);
 
 			return Mono.fromFuture(this.graphQlSource.graphQl().executeAsync(executionInputToUse))
+					.onErrorResume(GraphQLException.class, (exception) -> {
+						if (exception instanceof GraphQLError graphQLError) {
+							return Mono.just(ExecutionResult.newExecutionResult().addError(graphQLError).build());
+						}
+						return Mono.error(exception);
+					})
 					.map((result) -> new DefaultExecutionGraphQlResponse(executionInputToUse, result));
 		});
 	}

spring-graphql/src/test/java/org/springframework/graphql/execution/DefaultExecutionGraphQlServiceTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -18,6 +18,7 @@ package org.springframework.graphql.execution;
 
 import java.util.Map;
 
+import graphql.ErrorType;
 import org.dataloader.DataLoaderRegistry;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
@@ -28,6 +29,7 @@ import org.springframework.graphql.ExecutionGraphQlRequest;
 import org.springframework.graphql.ExecutionGraphQlResponse;
 import org.springframework.graphql.GraphQlSetup;
 import org.springframework.graphql.TestExecutionRequest;
+import org.springframework.graphql.support.DefaultExecutionGraphQlRequest;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -35,7 +37,6 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Unit tests for {@link DefaultExecutionGraphQlService}.
  *
  * @author Rossen Stoyanchev
- * @since 1.2.4
  */
 public class DefaultExecutionGraphQlServiceTests {
 
@@ -64,4 +65,18 @@ public class DefaultExecutionGraphQlServiceTests {
 		assertThat(dataLoaderRegistry.getDataLoaders()).hasSize(1);
 	}
 
+	@Test
+	void shouldHandleGraphQlErrors() {
+		GraphQlSource graphQlSource = GraphQlSetup.schemaContent("type Query { greeting: String }")
+				.queryFetcher("greeting", (env) -> "hi")
+				.toGraphQlSource();
+		DefaultExecutionGraphQlService graphQlService = new DefaultExecutionGraphQlService(graphQlSource);
+
+		ExecutionGraphQlRequest request = new DefaultExecutionGraphQlRequest("{ greeting }", "unknown",
+				null, null, "uniqueId", null);
+		ExecutionGraphQlResponse response = graphQlService.execute(request).block();
+		assertThat(response.getExecutionResult().getErrors()).singleElement()
+				.hasFieldOrPropertyWithValue("errorType", ErrorType.ValidationError);
+	}
+
 }