fix: remove deprecated util.isError usage

Author: aryamohanan

lib/error.js

@@ -407,7 +407,12 @@ function LibrdKafkaError(e) {
       this.origin = 'kafka';
     }
     Error.captureStackTrace(this, this.constructor);
-  } else if (e instanceof Error || Object.prototype.toString.call(e) === '[object Error]') {
+  } else if (
+    !(
+      e instanceof Error ||
+      Object.prototype.toString.call(e) === "[object Error]"
+    )
+  ) {
     // This is the better way
     this.message = e.message;
     this.code = e.code;