launch: improve validation warning for unexpected properties

Change the validation warning issued when unexpected properties are
found in the REANA specification to include the path to were the
invalidating keywords were found.

Closes reanahub/reana-client#679.

reana-ui/src/pages/launchOnReana/LaunchOnReana.js

@@ -46,7 +46,16 @@ export default function LaunchOnReana() {
             // Iterate over all keys in validation_warning
             for (const key in validation_warnings) {
               if (key === "additional_properties") {
-                const properties = validation_warnings[key].join(", ");
+                const properties = validation_warnings[key]
+                  .map(
+                    (additionalProperty) =>
+                      `${additionalProperty.property}${
+                        additionalProperty.path
+                          ? ` (at ${additionalProperty.path})`
+                          : ""
+                      }`,
+                  )
+                  .join(", ");
                 warningMessages.push(
                   `Unexpected properties found in the REANA specification: ${properties}.`,
                 );