Improved error logs when missing 'using' configuration in metadata file

src/Runner.Worker/ActionManifestManager.cs

@@ -503,7 +503,7 @@ private ActionExecutionData ConvertRuns(
                 };
             }
 
-            throw new NotSupportedException(nameof(ConvertRuns));
+            throw new NotSupportedException("Missing 'using' value. 'using' requires 'composite', 'docker', 'node12' or 'node16'.");
         }
 
         private void ConvertInputs(

src/Test/L0/Worker/ActionManifestManagerL0.cs

@@ -698,6 +698,31 @@ public void Load_ConditionalCompositeAction()
             }
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Load_CompositeActionNoUsing()
+        {
+            try
+            {
+                //Arrange
+                Setup();
+
+                var actionManifest = new ActionManifestManager();
+                actionManifest.Initialize(_hc);
+                var action_path = Path.Combine(TestUtil.GetTestDataPath(), "composite_action_without_using_token.yml");
+
+                //Assert
+                var err = Assert.Throws<ArgumentException>(() => actionManifest.Load(_ec.Object, action_path));
+                Assert.Contains($"Fail to load {action_path}", err.Message);
+                _ec.Verify(x => x.AddIssue(It.Is<Issue>(s => s.Message.Contains("Missing 'using' value. 'using' requires 'composite', 'docker', 'node12' or 'node16'.")), It.IsAny<string>()), Times.Once);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]

src/Test/TestData/composite_action_without_using_token.yml

@@ -0,0 +1,9 @@
+name: "composite action"
+description: "test composite action without value for the 'using' token in 'runs'"
+
+runs:
+  steps:
+    - id: mystep
+      shell: bash
+      run: |
+        echo "hello world"