In ExtendScriptDebugger for vscode, If I assign a number to a variable and it doesn't reflect well .

I am trying to create an extension in adobe premier pro using extendScript debugger for vscode.

I have run the following debugging in a jsx file

[[[
thisClip.start.seconds = 4;
$.writeln("\nthisClip.start.seconds >> ",thisClip.start.seconds);
]]]

The following output was generated.
[[[
thisClip.start.seconds >> 1
]]]

I also ran the following code

[[[
var project = app.project;

var sequence = project.activeSequence;
var videoTracks = sequence.videoTracks;
//var thisTrack = videoTracks[3];
var thisTrack = videoTracks[0];
var clips = thisTrack.clips;
var thisClip = clips[0];

alert(thisClip.duration.seconds);
alert(thisClip.end.seconds);
alert(thisClip.inPoint.seconds);
alert(thisClip.outPoint.seconds);
alert(thisClip.start.seconds);

]]]]]

I get the following error

[[[[
Exception has occurred: 1
Illegal Parameter type

]]]]

If I assign a number to a variable and it doesn't reflect well, how do I solve it?