[Issue 19091] __traits(compiles) and error in templated structs leads to missing symbol

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19091

--- Comment #2 from FeepingCreature <default_357-line at yahoo.de> ---
Found a new version of this bug:

```
void early()() { Struct!() var; }

struct Struct() { void fun() { error; } }

void main() {
    void helper()() { early; }

    static assert(!__traits(compiles, helper()));
    helper();
}
```

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