Null conditional await

While reviewing a codebase I noticed the following C# snippet:

What we are trying to do here is to simplify the null check on the transaction object by using a null-conditional operator (?.)

However this doesn’t work as expected when using async/await. If we would try to execute the code as-is, we would get a NullReferenceException when the transaction object is null. Exactly the thing we are trying to avoid.

This is something that you can already notice if you look at the compiler warning we get:

The reason is that our await call- even if there's no result value – expect to get a Task object back. Instead the result is null and the compiler generated async\await code internally can't deal with the null value. Hence the NullReferenceException when a value of Task is expected.

If you really want to use the null-conditional operator you could rewrite the code like this:

More information:

Member access and null-conditional operators and expressions: - C# | Microsoft Learn

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A complex system designed from scratch never works

A few years ago, I worked as an architect on a big mainframe rewrite. I still count it as one of my failures. Not because the technology was wrong, but because I couldn't convince the management team to simplify the approach. Years later, the organization is still struggling to get the new system up and running. I left the project at the time, because I couldn't put my name behind an approach that would take very long and cost a lot of money without a working system to show for it along the way. Gall’s Law That memory keeps coming back to me, because it's a textbook case of Gall's Law playing out in real life. Gall's Law , from John Gall's Systemantics , states it plainly: A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works, and it cannot be patched to make it work. You have to start over with a simple system that works. What does that mean in practice,...

The art of simplicity

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