Image: throw exception when $file and $type is null

[vlastavesely]

Fixes problem with calling 'pathinfo()' with null filename.

• bug fix? yes
• BC break? no

[f3l1x]

Maybe file should be not null? I'm not sure, just wondering.. @dg ?

[vlastavesely]

Image::send() calls the save() function with $file being set to NULL and you can never be sure whether someone does not use the same way in their application. I think that it would be a BC. My solution just converts confusing typehint error to more understandable exception.

[vlastavesely]

@dg What does it solve? Image::save() still can be called with no arguments and thus emit TypeError (pathinfo() expects parameter 1 to be string, null given).

[dg]

Fixed