Fail when an unpickle succeeds but has extra junk data at the end.

Also adds tests to ensure this is working.
2 jobs for dkasak/fix-unpickling-error-handling in 2 minutes and 28 seconds (queued for 31 seconds)
Child pipeline (parent)
Status Job ID Name Coverage
  Build
passed build:js #24158

00:01:28

 
  Test
passed test:js #24161

00:01:00