* [Schema] Fix Implementation::fromArray rejecting falsy-but-valid name/version
`empty()` treats the string "0" as empty, so a valid clientInfo/serverInfo
with `"version": "0"` (or `"name": "0"`) was rejected with an
InvalidArgumentException. During initialize this aborted request parsing and
surfaced as a misleading "A valid session id is REQUIRED" error.
Replace the `empty()` guards with explicit isset/is_string/empty-string checks
so genuinely missing, non-string, and empty values are still rejected while
"0" is accepted. Adds ImplementationTest covering the regression and the
existing validation paths.
Fixes#392
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* [Schema] Suppress PHPStan argument.type on invalid-input tests
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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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