fixes bug #4466

The accessed elements don’t have the nested levels and such all call
result in the rescue block.
fixed Error: undefined method `[]' for nil:NilClass

removed nesting level
Merge pull request #90 from StephanDollberg/4466_os_info

Fixes bug #4466
Merge pull request #92 from StephanDollberg/4471_sc_nil_error

Fixed Error: undefined method `[]' for nil:NilClass
fixes bug #4467

Added rescue statement which covers the case when the media has no
associated OS ids
DataField merged into Field
Merge pull request #88 from tstrachota/fields

DataField merged into Field
Merge pull request #91 from StephanDollberg/4467_media_os_ids

Fixes bug #4467