only_throw_errors

Don't throw instances of classes that don't extend either 'Exception' or 'Error'.

The analyzer produces this diagnostic when the value being thrown isn't a subclass of either Exception or Error.

The following code produces this diagnostic because the string 'f' is being thrown:

void f() => throw 'f';

Replace the value with an instance of a subclass of either Exception or Error:

void f() => throw ArgumentError('f');