Use data_get to safely retrieve $sourceDetail value (#911)
Use data_get to safely retrieve $sourceDetail value (#911)

We're seeing disparity between development environment where this is _not_ triggering an unefined index error for `null` $sourceDetails and QA where it _is_ triggering this error.

We'll continue looking into this. This fix is for now.
DoSomething/northstar,DoSomething/northstar,DoSomething/northstar