fix(tvix/eval): reduce scope depth in scope module

Change-Id: If32f9e4c9212f20a39baa15d479ff1387c17570d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6500
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

tvix/eval/src/compiler/scope.rs

@@ -310,6 +310,8 @@ impl Scope {
             }
         }
 
+        self.scope_depth -= 1;
+
         (pops, unused_spans)
     }
 }