app.xlsm

It is a long set of codes. If you have time, please help look at it.
The error is

Run-time error '91':
Object variable or With block variable not set

When I select Cells A7 and A8,
run Sub Sheet1.t2.
The error will occur.

I have commented where I guess (just I guess) the error comes from
as
when I deleted the code
The error does not come out
but
it cannot function as expected (use the newly opened tab)
My intention was to open a new tab in IE
and
use the new tab

I have worked on it for many hours.
So if you can help test the codes, I would be grateful for your help.


Many thanks in advance.

app1.xlsm

Edited.
You can see the change in the comment blocks.
Still an error coming out.

app2.xlsm

The resolution, to my amazement, is desperate.
By adding
before each time
The error does not emerge.

Very long time age I discovered the "trick" of it, but
I hate using it as I dunno... anyway just thought it was not a proper way to tackle run-time errors. Whenever I couldn't explain why the error exists and find the right way to resolve it, just using a hard way... is not going to help me improve my scripting knowledge a lot.
Anyway, don't know what I'm talking about. If anyone knows why the run-time error exists, please do teach me a thing. Thank you in advance.

P.S.:
Indeed, the error normally emerges 3 - 4 times out of 10 trials.