"999 is enough for anybody" triple-zero padding (#18)

When I hit 999 exercises, I will finally have reached the ultimate
state of soteriological release and no more exercises will be needed.
The cycle will be complete. All that will be left is perfect quietude,
freedom, and highest happiness.

exercises/022_errors2.zig

@@ -0,0 +1,29 @@
+//
+// A common case for errors is a situation where we're expecting to
+// have a value OR something has gone wrong. Take this example:
+//
+//     var text: Text = getText('foo.txt');
+//
+// What happens if getText() can't find 'foo.txt'?  How do we express
+// this in Zig?
+//
+// Zig lets us make what's called an "error union" which is a value
+// which could either be a regular value OR an error from a set:
+//
+//     var text: MyErrorSet!Text = getText('foo.txt');
+//
+// For now, let's just see if we can try making an error union!
+//
+const std = @import("std");
+
+const MyNumberError = error{TooSmall};
+
+pub fn main() void {
+    var my_number: ??? = 5;
+
+    // Looks like my_number will need to either store a number OR
+    // an error. Can you set the type correctly above?
+    my_number = MyNumberError.TooSmall;
+
+    std.debug.print("I compiled!", .{});
+}