How do you debug a channel?

Hi! Something in my `local' channel causes this error when I execute `guix pull': building /gnu/store/blb4jxbhdckbpcqf46yk74jrml1ds7wy-local.drv... -builder for `/gnu/store/blb4jxbhdckbpcqf46yk74jrml1ds7wy-local.drv' failed to produce output path `/gnu/store/2klsbdwip925viqv5q8qla4zvnjqqr1i-loca

How do you debug a channel?

Hi! Something in my `local' channel causes an error when I execute `guix pull': building /gnu/store/blb4jxbhdckbpcqf46yk74jrml1ds7wy-local.drv... -builder for `/gnu/store/blb4jxbhdckbpcqf46yk74jrml1ds7wy-local.drv' failed to produce output path `/gnu/store/2klsbdwip925viqv5q8qla4zvnjqqr1i-local'