Log MySQL Errors

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This PR will improve error handling in the MySQL driver by making the following changes:

• Fix errors from mysql_query() being ignored.
• Fix errors from mysql_store_result() being ignored.
• Fix errors from mysql_real_escape_string() being ignored.
• Fix "errors" pretending to be warnings.
• Fix error-propagation failures.
• Fix errors not being marked as resolved.
• Fix errors being cleared when they weren't resolved.
• Add more error messages.
• Add expect to reduce performance hit from checking for errors.

Useful C MySQL lib docs:

• https://dev.mysql.com/doc/c-api/8.0/en/mysql-error.html
• https://dev.mysql.com/doc/c-api/8.0/en/mysql-errno.html
• https://dev.mysql.com/doc/c-api/8.0/en/mysql-real-escape-string.html
• https://dev.mysql.com/doc/c-api/8.0/en/mysql-query.html
• https://dev.mysql.com/doc/c-api/8.0/en/mysql-store-result.html

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@greptileai Please review this PR.

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Greptile Summary

This PR improves error visibility in the MySQL object driver by propagating previously-ignored failures from mysql_query, mysql_store_result, and mysql_real_escape_string through mssError, and refactors mssError itself from a custom format parser to vsnprintf with a void return type.

• mssError rewrite (mtsession.c/mtsession.h): return type changed from int to void, format handling delegated to vsnprintf, session-context logging preserved; all 93 affected callers updated across the PR.
• MySQL driver error handling (objdrv_mysql.c): mysql_query and mysql_store_result failures now log an mssError before returning MYSD_RUNQUERY_ERROR; DML NULL-result handling is correctly preserved; mysql_real_escape_string failure is now detected and reported; goto-based cleanup consolidates previously duplicated teardown code.
• New check/check_ptr diagnostic macros (util.h/util.c): lightweight wrappers that print developer diagnostics (file, line, errno) when a function returns an unexpected value, used to surface allocation and library-init failures without changing control flow.

Confidence Score: 5/5

The changes are additive error-logging improvements; the DML NULL-result regression flagged in earlier review rounds has been fixed, and no new data-path logic was introduced.

All previously identified correctness issues were addressed in prior review rounds. The remaining findings are style-level: a dead variable, a misleading goto label, and a pointer-to-integer-literal comparison. The core control flow is correct.

centrallix/osdrivers/objdrv_mysql.c and centrallix-lib/src/mtsession.c carry the bulk of the functional change and are worth a final read-through.

Important Files Changed

Filename	Overview
centrallix/osdrivers/objdrv_mysql.c	Core change: adds mssError calls after previously-silent failures, fixes DML NULL-result handling, introduces goto-based cleanup, and checks mysql_real_escape_string return value. A dead variable and a misleading goto label remain; functionally the logic is correct.
centrallix-lib/src/mtsession.c	mssError rewritten: return type changed from int to void, custom format parser replaced with vsnprintf into a fixed BUFSIZ buffer, session list handling preserved.
centrallix-lib/include/mtsession.h	Declaration of mssError updated from int to void to match the new implementation; no other functional changes.
centrallix-lib/include/util.h	Adds check/check_neg/check_ptr/check_double diagnostic macros, min/max via GCC statement expressions, Timer API, and formatting utilities; all wrapped with appropriate include guards.
centrallix-lib/src/util.c	Implements the new utilities declared in util.h; all additions are additive and do not touch existing strtoi/strtoui logic.
centrallix-lib/include/expect.h	Adds conditional inclusion of cxlibconfig.h so HAVE_BUILTIN_EXPECT is available; reformats existing LIKELY/UNLIKELY macros with no logic change.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["mysd_internal_RunQuery_conn_va()"] --> B["Build query string\n(SafeAppend for each param)"]
    B -- "SafeAppend fails" --> ERR1["mssError(1) escape error\ngoto error"]
    B -- "Success" --> C["mysql_query()"]
    C -- "Returns != 0" --> ERR2["mssError(1) query error\ngoto query_error"]
    C -- "Returns 0" --> D["mysql_store_result()"]
    D --> E{"mysql_errno() != 0?"}
    E -- "Yes (real error)" --> ERR3["mssError(1) store error\nfree result\ngoto error"]
    E -- "No (DML = NULL is OK)" --> F["rval = query_result\ngoto cleanup"]
    ERR1 --> CLEANUP
    ERR2 --> CLEANUP["cleanup:\nif rval == ERROR\n  mssError(0) context msg\nxsDeInit(query)\nreturn rval"]
    ERR3 --> CLEANUP
    F --> CLEANUP
    CLEANUP --> G["Return MYSD_RUNQUERY_ERROR\nor valid MYSQL_RES*"]

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@greptileai Please re-review this PR. Any other issues? Let me know if it looks good.

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Warning: This PR is blocked behind the following PRs. Please review them first and review this PR after they have been merged into master so that their changes will not appear in the diff for this PR.

• Include mssError() when used #98
• Update Duplicate Detection #77

We should rebase this branch before merging to clean up merge commit mayhem.

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This PR is ready for human review (after the blockers are resolved).