Update helpers.js

Is there a problem here? Yes, there is. Please take a look at this error.

TypeError: Cannot read properties of undefined (reading 'indexOf')
    at Object.parseMask (/home/debian/node/client/server/libs/irc-framework-modded/src/helpers.js:20:23)
    at Array.RPL_TOPICWHOTIME (/home/debian/node/client/server/libs/irc-framework-modded/src/commands/handlers/channel.js:198:32)
    at IrcCommandHandler.executeCommand (/home/debian/node/client/server/libs/irc-framework-modded/src/commands/handler.js:65:40)
    at IrcCommandHandler.dispatch (/home/debian/node/client/server/libs/irc-framework-modded/src/commands/handler.js:52:18)
    at /home/debian/node/client/server/libs/irc-framework-modded/src/client.js:129:40
    at next (/home/debian/node/client/server/libs/irc-framework-modded/node_modules/middleware-handler/index.js:42:18)
    at MiddlewareHandler.handle (/home/debian/node/client/server/libs/irc-framework-modded/node_modules/middleware-handler/index.js:64:3)
    at Connection.<anonymous> (/home/debian/node/client/server/libs/irc-framework-modded/src/client.js:123:35)
    at Connection.emit (/home/debian/node/client/server/libs/irc-framework-modded/node_modules/eventemitter3/index.js:182:35)
    at Connection.addReadBuffer (/home/debian/node/client/server/libs/irc-framework-modded/src/connection.js:168:14)

src/helpers.js

@@ -17,8 +17,10 @@ function parseMask(mask) {
     let user = '';
     let host = '';
 
-    const sep1 = mask.indexOf('!');
-    const sep2 = mask.indexOf('@');
+    //const sep1 = mask.indexOf('!');
+    const sep1 = (mask || '').indexOf('!');
+    //const sep2 = mask.indexOf('@');
+    const sep2 = (mask || '').indexOf('@');
 
     if (sep1 === -1 && sep2 === -1) {
         // something