Detailed steps to reproduce the problem?

Repro: https://github.com/10gen/go-driver-tools/blob/main/preston/repros/2.9.2/godriver_4190_test.go
Public Repro: https://gist.github.com/prestonvasquez/fc120e56dc8116f3a77739ca11cb6c5d

Definition of done: what must be done to consider the task complete?

The documentation for SingleResult.Decode states

If there was an error from the operation that created this DistinctResult, that error will be returned.

We need to add a guard to SingleResult.Decode:

if dr.err != nil {
    return dr.err
}

The exact Go version used, with patch level:

NA

The exact version of the Go driver used:

2.9.2

Describe how MongoDB is set up. Local vs Hosted, version, topology, load balanced, etc.

NA

The operating system and version (e.g. Windows 7, OSX 10.8, ...)

NA

Security Vulnerabilities

NA