diff --git a/headless-services/concourse-language-server/src/test/java/org/springframework/ide/vscode/concourse/ConcourseEditorTest.java b/headless-services/concourse-language-server/src/test/java/org/springframework/ide/vscode/concourse/ConcourseEditorTest.java
index 87bd528c7..3dd75ef16 100644
--- a/headless-services/concourse-language-server/src/test/java/org/springframework/ide/vscode/concourse/ConcourseEditorTest.java
+++ b/headless-services/concourse-language-server/src/test/java/org/springframework/ide/vscode/concourse/ConcourseEditorTest.java
@@ -4944,6 +4944,39 @@ public class ConcourseEditorTest {
 		);
 	}
 
+	@Test
+	public void reconcileMalformedMergeNode() throws Exception {
+		Editor editor = harness.newEditor(
+				"resources:\n" +
+				"- name: foo\n" +
+				"  type: git\n" +
+				"  source:\n" +
+				"    <<: scalar\n"
+		);
+		editor.assertProblems(
+				"foo|Unused",
+				"source|'uri' is required",
+				"scalar|Expected a mapping or list of mappings"
+		);
+	}
+
+	@Test
+	public void reconcileMalformedMergeNodeList() throws Exception {
+		Editor editor = harness.newEditor(
+				"resources:\n" +
+				"- name: foo\n" +
+				"  type: git\n" +
+				"  source:\n" +
+				"    <<:\n" +
+				"    - scalar\n"
+		);
+		editor.assertProblems(
+				"foo|Unused",
+				"source|'uri' is required",
+				"scalar|Expected a mapping for merging"
+		);
+	}
+
 	@Test
 	public void anchorsAndReferenceSample_1() throws Exception {
 		Editor editor = harness.newEditor(