Summary:
I need help debugging this issue and perhaps figuring out what pins should be used for the audio and SD reader components.
The example used is the pipeline_play_sdcard_music, which produces the error listed below.
I am using a custom board definition, which is attached here.
Importantly ...

In my experience, you have to modify get_i2s_pins in board_pins_config.c
I have explored why, but the ESP_SD_PIN* macros in board_def.h don't seem to be used.