Support backward compatibility for runtime's return type (#5306)

Author: upgle

tests/src/test/scala/actionContainers/BasicActionRunnerTests.scala

@@ -173,7 +173,9 @@ trait BasicActionRunnerTests extends ActionProxyContainerTestUtils {
         initCode should be(200)
         val (runCode, out) = c.run(JsObject.empty)
         runCode should not be (200)
-        out should be(Some(JsObject("error" -> JsString("The action did not return a dictionary or array."))))
+
+        out should (be(Some(JsObject("error" -> JsString("The action did not return a dictionary or array.")))) or be(
+          Some(JsObject("error" -> JsString("The action did not return a dictionary.")))))
       }
 
       checkStreams(out, err, {