If a developer doesn't check for a null value, are you really going to head to the documentation to find out why? Is the segfault really by-design? It might sound facetious, but that's the 90% of bugs: not specifically segfaults, but trivial mistakes, invalid values and logic problems. Only a debugger can show you the steps and conditions involved that lead to that invalid value. Sometimes, through debugging, you find a problem that does span multiple layers or components.
If something spans multiple layers or components then that's a design problem. When you are solving a bug like this you have to "debug" at a much higher abstraction level. You shouldn't use a debugger for this (as you've pointed out); you should use a team of peers (documentation alone is not the correct tool). That team might rely on documentation, but would have to keep in mind that documentation rots over time.
If you're solving the former with the processes of the latter, I'm surprised you get anything done. Documentation won't tell you where an invalid value originates from or why. Only extremely verbose logging or debugging can do that.
If a developer doesn't check for a null value, are you really going to head to the documentation to find out why? Is the segfault really by-design? It might sound facetious, but that's the 90% of bugs: not specifically segfaults, but trivial mistakes, invalid values and logic problems. Only a debugger can show you the steps and conditions involved that lead to that invalid value. Sometimes, through debugging, you find a problem that does span multiple layers or components.
If something spans multiple layers or components then that's a design problem. When you are solving a bug like this you have to "debug" at a much higher abstraction level. You shouldn't use a debugger for this (as you've pointed out); you should use a team of peers (documentation alone is not the correct tool). That team might rely on documentation, but would have to keep in mind that documentation rots over time.
If you're solving the former with the processes of the latter, I'm surprised you get anything done. Documentation won't tell you where an invalid value originates from or why. Only extremely verbose logging or debugging can do that.