Internal error: '=destroy' operator not found for type

[al6x]

Description

This code would crash compiler

type Person = object

type Builder* = ref object of RootObj
  class*: typedesc

echo Builder(class: Person).repr

Nim Version

Nim Compiler Version 1.6.12 [MacOSX: amd64] Compiled at 2023-03-10 Copyright (c) 2006-2023 by Andreas Rumpf

active boot switches: -d:release -d:nimUseLinenoise

Current Output

It produces different errors, on my machine it's 

Hint: used config file '/usr/local/Cellar/nim/1.6.12/nim/config/nim.cfg' [Conf]
Hint: used config file '/usr/local/Cellar/nim/1.6.12/nim/config/config.nims' [Conf]
.........................................................
/alex/projects/nim/play.nim(10, 13) Error: internal error: '=destroy' operator not found for type Builder

in playground its

Error: internal error: getTypeDescAux(tyNone)
No stack traceback available
To create a stacktrace, rerun compilation with './koch temp c <file>', see https://nim-lang.github.io/Nim/intern.html#debugging-the-compiler for details

### Expected Output

_No response_

### Possible Solution

_No response_

### Additional Information

_No response_

[beef331]

typedesc is not a runtime value should error inside typedefinition.

[al6x]

Also, the compilation error message for this code should be improved, currently it prints cryptic error and it's hard to understand what's wrong (the problem is typedesc field in Element):

import std/tables

type Element* = ref object of RootObj
  tag*:               typedesc

type App* = ref object of RootObj
  children*:         seq[Element]

type Apps* = ref Table[string, App]

proc build*(apps: Apps): App =
  discard

prints

play.nim(13, 12) Error: invalid type: 'Table[system.string, play.App]' in this context: 'proc (apps: Apps): App' for proc