Reset Lua stack to drop unused returned values

Since some Lua code may return values that will be left on stack, they
need to be removed to avoid growing the stack unnecessarily.

tool/net/redbean.c

@@ -176,6 +176,7 @@ STATIC_YOINK("zip_uri_support");
       char *s = LuaFormatStack(L);                \
       WARNF("lua stack should be empty!\n%s", s); \
       free(s);                                    \
+      lua_settop(L, 0);                           \
     }                                             \
   } while (0)
 
@@ -1065,9 +1066,9 @@ static bool LuaOnClientConnection(void) {
     dropit = lua_toboolean(L, -1);
   } else {
     LogLuaError("OnClientConnection", lua_tostring(L, -1));
-    lua_pop(L, 1);  // pop error
     dropit = false;
   }
+  lua_pop(L, 1);  // pop result or error
   AssertLuaStackIsEmpty(L);
   return dropit;
 #else