Delaying error handlers

Description

Due to error handlers, some operations may have unsuspected effects. This is the cause of bugs and workarounds. Quoting GH-6903:

[...] long-standing source of interrupt
vulnerabilities: A notice is emitted during execution of an opcode,
resulting in an error handling being run. The error handler modifies
some data structure the opcode is working on, resulting in UAF or
other memory corruption.

These bugs and workarounds could be avoided by delaying error handlers until a safepoint. Existing/Previous work:

• https://github.com/php/php-src/pull/6903
• https://github.com/php/php-src/pull/7735
• https://github.com/php/php-src/pull/12090
• https://github.com/php/php-src/pull/12805

I'm creating this ticket to aggregate issues that would not exist with delayed error handlers:

• https://github.com/php/php-src/issues/13754
• https://github.com/php/php-src/issues/15907
• https://github.com/php/php-src/issues/16726
• https://github.com/php/php-src/issues/17416
• https://github.com/php/php-src/issues/18043
• https://github.com/php/php-src/issues/18274
• https://github.com/php/php-src/issues/20042
• https://github.com/php/php-src/issues/20482
• https://github.com/php/php-src/issues/20855
• https://github.com/php/php-src/issues/21024
• https://github.com/php/php-src/issues/21245

Inizia esaminando le pull request precedenti 6903, 7735, 12090 e 12805, quindi esamina le issue collegate raccolte qui. Il lavoro è completo quando i gestori degli errori vengono posticipati fino a un safepoint, così che i bug e i workaround relativi alle interruzioni elencati non siano più applicabili.