Collect error messages from failed conditions

[kopsha]

Currently, the may_<trigger>() methods return a simple boolean indicating whether a trigger is allowed given the current state and its conditions.

I wonder if it would be useful to allow collecting a list of messages about which conditions failed.

For example:

flow.may_install()  
# Returns: False  

# Proposed behavior:
flow.may_install(collect_fails=True)
# Returns:
[
    {"condition": "has_installation_report", "message": "Please upload an installation report first."},
]
# or maybe even the complete list of conditions
[
    {"condition": "has_installation_report", "result": False, "message": "Please upload an installation report first."},
    {"condition": "has_quality_approval", "result": True, "message": ""}
]

Benefits:

• Provides actionable diagnostics for UI/UX or API feedback without raising exceptions.
• Helps developers debug state machine failures more efficiently.
• Keeps business logic (conditions) self-contained while making transitions introspectable.
• Default behavior remains backward-compatible, returning a simple boolean.

[kopsha]

After reading the documentation thoroughly, I noticed that all arguments passed to trigger or may_<trigger> are forwarded to all evaluated conditions and callbacks. And this allows me to pass any error messages through exceptions, which is not a terrible design choice.