New v3 path error message should distinguish between "lack of key" and "key equals null"

[zerkms]

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Type\shape(['foo' => Type\string()], true)->assert([]);
Type\shape(['foo' => Type\string()], true)->assert(['foo' => null]);

Both these two evaluations result in a AssertException with a Expected "array{'foo': string}", got "null" at path "foo". message.

It's misleading as the lack of the key is definitely different beast to the key that is = null.

Describe the solution you'd like
I would prefer two distinct messages (non-native speaker here, so needs polishing):

Expected "array{'foo': string}", path "foo" does not exist.
Expected "array{'foo': string}", got "null" at path "foo".

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[veewee]

Hi @zerkms,

That sure is possible. Care to give it a PR?
Related exception lines in code:

• psl/src/Psl/Type/Internal/ShapeType.php

  Line 147 in 6683d60

  throw CoercionException::withValue(null, $this->toString(), PathExpression::path($element));

• psl/src/Psl/Type/Internal/ShapeType.php

  Line 199 in 6683d60

  throw AssertException::withValue(null, $this->toString(), PathExpression::path($element));

[zerkms]

Related exception lines in code:

Yep, I already debugged through it :-) It was also to confirm whether the corresponding change would be accepted/welcomed overall.