unused err value and nil context

Incorrect err assignment had no effect.

Never use a nil context.

backend/remote/backend_common.go

@@ -495,10 +495,10 @@ func (b *Remote) confirm(stopCtx context.Context, op *backend.Operation, opts *t
 					}
 
 					if err == errRunDiscarded {
+						err = errApplyDiscarded
 						if op.Destroy {
 							err = errDestroyDiscarded
 						}
-						err = errApplyDiscarded
 					}
 
 					result <- err

backend/remote/backend_context_test.go

@@ -195,7 +195,7 @@ func TestRemoteContextWithVars(t *testing.T) {
 				key := "key"
 				v.Key = &key
 			}
-			b.client.Variables.Create(nil, workspaceID, *v)
+			b.client.Variables.Create(context.TODO(), workspaceID, *v)
 
 			_, _, diags := b.Context(op)