S0054: err pattern requires Result

Generated from rellum-diagnostics/src/db.rs.

Explanation

The err(...) pattern extracts the error payload from a Result value. It cannot match Option, Bool, enum, record, or scalar values because those types do not have Result's ok/err shape.

Common causes

• using err(e) while matching an Option
• matching a plain value as if it were a Result
• forgetting that a request handler has already converted the raw Result

Canonical fixes

• match a Result value with ok and err arms

Before:

match value
    err(e) => fallback

After:

match result
    ok(v) => v
    err(e) => fallback

• use some/none when matching Option

Before:

match value
    err(e) => fallback

After:

match value
    some(v) => v
    none => fallback

Code example

match value
    err(e) => fallback

Links

• RellC diagnostic overview