One idea I had that could be a component of the solution would be that all
spec-thrown exceptions get an extra flag. So e.g.
```js
try {
iDoNotExist();
} catch (e) {
assert(e.thrownBySpecMechanisms);
}
```
You would generally use this via
```js
try {
someOperation();
} catch (e) {
if (e.thrownBySpecMechanisms) {
// I am only prepared to handle operational failures, not typos or
// trying to write to non-writable properties or the like.
throw e;
}
handleOperationalError(e);
}
```
You could then imagine some syntactic sugar of the sort
```js
try {
someOperation();
} recover (e) {
// `recover` only handles non-spec-thrown exceptions.
handleOperationalError(e);
}
```
This would be an alternative to the requirement that all authors suddenly agree
on a new flag (or worse, subclass) to distinguish their errors from spec-thrown
errors, and then do
```js
try {
someOperation();
} catch (e) {
if (!e.crossLibraryStandardFlagForLibraryThrownNotSpecThrown) {
throw e;
}
handleOperationalError(e);
}
```
which as per previous complaints on this thread also has the problem that you
lose stack trace information.
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