Nested IF statement?

So I was fiddling with the code today and tried every single variation of ISBLANK/COUNTROWS/II/&&/all the possible column names and table names, but nothing worked.  

When I removed ‘City Images JPG Base 64’[Selected Image]) from the ISBLANK function, the whole image disappeared and it said “Fix this.”  When I put it back in, it worked again.  So the problem must be with the COUNTROWS function.  If I take out COUNTROWS(‘City Images JPG Base 64’) altogether, it still works to the same degree.   

Image =

var img =

IF([SelectedImage]="Canada" ||

    COUNTROWS('City Images JPG Base 64')=0 && ISBLANK('City Images JPG Base 64'[SelectedImage]),

    "data:image/jpeg;base64, "&

    CONCATENATEX(FILTER

    ('City Images JPG Base 64',

    'City Images JPG Base 64'[Name]="Canada.jpg"),'City Images JPG Base 64'[Pic],,'City Images JPG Base 64'[Index],ASC),

IF(

    HASONEVALUE('City Images JPG Base 64'[Name]),

    "data:image/jpg;base64, " &

    CONCATENATEX

        ('City Images JPG Base 64',

        'City Images JPG Base 64'[Pic],

        ,

        'City Images JPG Base 64'[INDEX],ASC)

    )

)

RETURN img

So then I actually removed the 4th line altogether (ISBLANK...) and the code worked the same as it did without that line!!