Reproduction steps:
1. Create a new 3D project
2. In the Package Manager (“Window → Package Manager”), install the “High Definition RP“ package
3. Import and open the “Test.shadergraph”
4. Observe the “Yeah (Custom Function)“ node

Expected result: No errors appear
Actual result: “'isfinite': no matching 1 parameter intrinsic function; Possible intrinsic functions are: isfinite(float|half) at line X“ error appears

Reproducible with: 2021.3.47f1, 2022.3.55f1, 6000.0.33f1, 6000.1.0b1

Reproducible on: Windows 10 (22H2), Windows 11 (24H2) (reporter’s environment)
Not reproducible on: No other environments tested

Note: Adding a vector or float output as the first slot fixes the issue and works as a workaround