Bug: brew leaves returns error if one of installed formulas has untapped optional dependencies

[xu-cheng]

I installed homebrew/python/matplotlib. And in this formula it has an optional dependency homebrew/dupes/tcl-tk. As I didn't tap the homebrew/dupes, if I run brew leaves, it will show the following error:

$ brew leaves
Error: No available formula for tcl-tk
Please tap it and then try again: brew tap homebrew/dupes

[adamv]

Fixing this will involve having Formula#installed be able to handle FormulaNotFound exceptions and ignore them

[jacknagel]

The problem here is pervasive (it will happen in any code path that tries to get formula objects from dependency objects). I plan to address it in my deps refactor.

[MikeMcQuaid]

@xu-cheng Is this still an issue?

[ilovezfs]

Looks fixed https://gist.github.com/ilovezfs/7aed2aa8aed3ebb791cc9ad93355b847