system: print number of ops completed at point of failure

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

internal/system/op.go

@@ -94,6 +94,7 @@ func (sys *I) Commit() error {
 		// sp is set to nil when all ops are applied
 		if sp != nil {
 			// rollback partial commit
+			fmsg.VPrintf("commit faulted after %d ops, rolling back partial commit", len(sp.ops))
 			if err := sp.Revert(&Criteria{nil}); err != nil {
 				fmsg.Println("errors returned reverting partial commit:", err)
 			}