fix: check for req function onPluginInit in isCactusPlugin

interface i-cactus-plugin in the function isICactusPlugin is not
checking for required onPluginInit

Closes: #1277
Signed-off-by: Michael Courtin <[email protected]>

Author: m-courtin

packages/cactus-core-api/src/main/typescript/plugin/i-cactus-plugin.ts

@@ -76,6 +76,7 @@ export function isICactusPlugin(x: unknown): x is ICactusPlugin {
   return (
     !!x &&
     typeof (x as ICactusPlugin).getPackageName === "function" &&
-    typeof (x as ICactusPlugin).getInstanceId === "function"
+    typeof (x as ICactusPlugin).getInstanceId === "function" &&
+    typeof (x as ICactusPlugin).onPluginInit === "function"
   );
 }