fix(portalblocks): handle null/unset rows in sparse layout arrays

[ralflang]

When block layout arrays have gaps (sparse arrays), count() returns
lastindex+1 ignoring omitted indices and this causes all kinds of errors.
isset() and is_array() checks before calling count() fix this now.

[amulet1]

I am not sure this is the right thing to do.

If I undestand correctly, the _layout array can have non-consecutive indexes. And we want to go over each one that exists.

But the for loop only goes up to count($this->_layout), which could miss some indexes.

Example:

$this->_layout = [ 0 => $value1, 10 => $value2 ];

in this case $rows = 2 and the for loop would only check row 0 and 1, but not row 10.

Possible solutions:

• use foreach, need to redesign "if (isset($field['height'])) {" block as it refers to other rows (could they also be non-consecutive?)
• alternatively, avoid sparse arrays or make it non-sparse in the constructor?

[amulet1]

Drop $emptyrows (looks like it is assigned but never used).

[amulet1]

This should be moved to rowExists method (it has to be redesigned as it does not work correctly for sparse arrays).

[amulet1]

Possibly change to this to support sparse _layout array:

return isset($this->_layout[$row]) && is_array($this->_layout[$row]);

And then it can be used in the contructor.