[Issue 23983] Better error message when brace missing after `else`

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23983

--- Comment #1 from ryuukk_ <ryuukk.dev at gmail.com> ---
Example 2:

```
void main()
{
    int stuff = 0;
    version (Poxis)
    {
        stuff++;
    }
    else
        stuff++;
    }

    version (Poxis)
    {
        stuff++;
    }
    else
    {
        stuff++;
    } 
}
```

```
onlineapp.d(15): Error: no identifier for declarator `stuff`
onlineapp.d(15): Error: declaration expected, not `++`
onlineapp.d(19): Error: no identifier for declarator `stuff`
onlineapp.d(19): Error: declaration expected, not `++`
onlineapp.d(21): Error: unmatched closing brace
```

Error message is misleading now

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