Throw error when the build is successful but in fact broken due to errors

[tlylt]

Sometimes build succeeds even though there is a build error:

The overall action status is Green, so users might not even realize there's a problem

We should somehow give a warning, or fail the action job entirely when we detect errors in the console output of markbind build.

Reference: https://github.com/AY2324S1-CS2103T-W08-1/tp/actions/runs/6364130962/job/17280202044