fix: handle empty relevant msgs in from_can_message

[nyurik]

Prevent unreachable expression compiler warning generating from_can_message - simply return CanError::UnknownMessageId(id) error without the match statement.

[codecov]

Codecov Report

❌ Patch coverage is 53.33333% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/lib.rs	53.33%	1 Missing and 6 partials ⚠️

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[Copilot]

Pull request overview

This PR fixes unreachable code compiler warnings in the generated from_can_message function when DBC files contain no relevant messages. The fix detects empty message lists and generates a direct error return instead of a match statement with an unreachable Ok branch.

Changes:

• Modified code generation logic to detect empty message lists and emit simplified error handling code
• Updated snapshot tests to reflect the corrected generated code
• Removed tests from the exclusion list that now pass without compiler warnings

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/lib.rs	Added check for empty messages and conditional code generation to avoid unreachable expression warnings
tests/snapshots.rs	Removed 4 tests from BAD_TESTS list that now compile successfully
tests-snapshots/dbc-cantools/issue_62.snap.rs	Updated generated code to use direct error return instead of unreachable match
tests-snapshots/dbc-cantools/empty_ns.snap.rs	Updated generated code to use direct error return instead of unreachable match
tests-snapshots/dbc-cantools/cp1252.snap.rs	Updated generated code to use direct error return instead of unreachable match
tests-snapshots/dbc-cantools/bus_comment_bare_out.snap.rs	Updated generated code to use direct error return instead of unreachable match
tests-snapshots/dbc-cantools/bus_comment_bare.snap.rs	Updated generated code to use direct error return instead of unreachable match
tests-snapshots/dbc-cantools/issue_62.snap.stderr	Removed error snapshot as the file now compiles without warnings
tests-snapshots/dbc-cantools/empty_ns.snap.stderr	Removed error snapshot as the file now compiles without warnings
tests-snapshots/dbc-cantools/cp1252.snap.stderr	Removed error snapshot as the file now compiles without warnings
tests-snapshots/dbc-cantools/bus_comment_bare_out.snap.stderr	Removed error snapshot as the file now compiles without warnings
tests-snapshots/dbc-cantools/bus_comment_bare.snap.stderr	Removed error snapshot as the file now compiles without warnings

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