An example of the compiler error when get when we miss a return that a block requires

MissingReturn.m

#import "Example.h" // https://gist.github.com/hborders/2af9b39e27b62ef9e68c65085126fe4a

- (void)missingReturn {
  Example * _Nonnull fooExample = [[ExampleFoo alloc] initWithF:@"foo"
                                                              g:@"goo"];
  NSNumber * _Nonnull number =
  [ExampleSwitcher<NSNumber *> nonnullExampleFrom:fooExample
                                        switchFoo:^(ExampleFoo * _Nonnull foo_) {
    return @(foo_.f.length + foo_.g.length);
  }
                                              bar:^(ExampleBar * _Nonnull bar_) {
    // should be:
    // return @(bar_.b.length + bar.c.length);
    @(bar_.b.length + bar.c.length);
  }];
//^
// error: control reaches end of non-void block
}