The analyzer has detected a potential error when using the ternary operator "?:". Regardless of the condition's result, one and the same statement will be executed. There is very likely a typo somewhere in the code.
Consider the following, simplest, example:
int A = B ? C : C;
In either case, the A variable will be assigned the value of the C variable.
Let's see what such an error may look like in real-life code:
fovRadius = Math.Tan((rollAngleClamped % 2 == 0 ? cg.fov_x : cg.fov_x) * 0.52) * sdist;
This code has been formatted. In reality, though, it may be written in one line, so it's no wonder that a typo may stay unnoticed. The error here has to do with the member of the "fov_x" class being used both times. The correct version of this code should look as follows:
fovRadius = Math.Tan((rollAngleClamped % 2 == 0 ? cg.fov_x : cg.fov_y) * 0.52) * sdist;
According to Common Weakness Enumeration, potential errors found by using this diagnostic are classified as CWE-783.
You can look at examples of errors detected by the V3012 diagnostic.