[foreign-memaccess+abi] Integrated: Improve exception messages and simplify LayoutPath

[Per Minborg]

On Mon, 18 Sep 2023 08:30:42 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> This PR proposes to improve the exception messages in the internal `LayoutPath` class and also do some code simplifications.

This pull request has now been integrated.

Changeset: f0f35043
Author:    Per Minborg <pminborg at openjdk.org>
URL:       https://git.openjdk.org/panama-foreign/commit/f0f3504331f495539f871e00c7cac86b6eb0d095
Stats:     92 lines in 2 files changed: 67 ins; 6 del; 19 mod

Improve exception messages and simplify LayoutPath

Reviewed-by: jvernee

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PR: https://git.openjdk.org/panama-foreign/pull/886