fixed issue when calling a function with null as argument

Author: bheisen

Diff for: CHANGELOG.md

@@ -37,6 +37,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - invalid log message triggered when JSON return values are circular
 - multiple emitter registration under the same clientId
 - issue when loading files that are not ending with ".js"
+- issue when calling a remote function with null as part of the arguments
 
 ## [3.1.1] - Aug 17 2022
 

Diff for: browser/vrpc.js

@@ -1225,7 +1225,7 @@ class VrpcClient extends EventEmitter {
 
   _isEmitter (variable) {
     return (
-      typeof variable === 'object' &&
+      variable && typeof variable === 'object' &&
       variable.hasOwnProperty('emitter') &&
       variable.hasOwnProperty('event') &&
       typeof variable.emitter === 'object' &&