Cannot declare an anonymous proc with source code filters

### Nim Version

2.2.0

### Description

```nim
#? stdtmpl
#let a = proc () =
  # echo "hi"
#end
#a()
```



### Current Output

```text
does not compile, with


Error: 'end' does not close a control flow construct
```

### Expected Output

```text
"hi"


let a = proc () =
  echo "hi"

a()


This works
```

### Known Workarounds

_No response_

### Additional Information

_No response_