A proof-of-concept repo that demonstrates a bug that can occur when leveraging STJ sourcegenerated SerializerContext which are additionally configured at runtime using JsonSerializerOptions.

The asset file accuracyTrackerDto.json (found in the Assets folder) contains a JSON object that contains a property called "gridAcc", which contains "NaN" string values.

The bug occurs whenever the following conditions are met:

1. A source generated SerializerContext is used
2. The SerializerContext is configured at runtime using JsonSerializerOptions, which has it's NumberHandling property set to JsonNumberHandling.AllowNamedFloatingPointLiterals

The bug doesn't occur when the property in the class/struct itself is annotated with the JsonNumberHandling attribute, or when not using a SerializerContext at all.

The bug can be reproduced across all versions of System.Text.Json that support source generated SerializerContexts and has the JsonNumberHandling attribute (5.0.0 and up) as far as my testing went.