Fixes all TypeScript failures caused by enabling the `--strict`
flag for test source files. We also want to enable the strict
options for tests as the strictness enforcement improves the
overall codehealth, unveiled common issues and additionally it
allows us to enable `strict` in the `tsconfig.json` that is picked
up by IDE's.
PR Close#30993
The 'stringify' function prints an object as [Object object] which
is not very helpful in many cases, especially in a diagnostics
message. This commit changes the behavior to pretty print an object.
PR Close#22689