Unify DSL and SkSL error handling paths

Change-Id: I9772da0c0a61d5fdb3114cd836053275bfb359df
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/436156
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
4 files changed