When certain validation errors occur a default density_data meta value is created as a string of '0,0' but when the data is processed it expects it to be an array.
Updates those places in the validation method to use an array of [ 0, 0 ] so it matches what is expected when processing.
Adds some additional checks before processing or accessing it to ensure it is an array.
Adds a test case that validates the issue is fixed
When certain validation errors occur a default density_data meta value is created as a string of
'0,0'but when the data is processed it expects it to be an array.[ 0, 0 ]so it matches what is expected when processing.Fixes: #548