Print threadid before failure

Author: penelopeysm

test/threadsafe.jl

@@ -60,6 +60,7 @@
         @time wthreads(x)(vi)
 
         # Ensure that we use `ThreadSafeVarInfo` to handle multithreaded observe statements.
+        @info "Threads.threadid() = $(Threads.threadid())"
         DynamicPPL.evaluate_threadsafe!!(
             wthreads(x),
             vi,