Fix vault standard examples

[SwayStar123]

Type of change

• Bug fix

Changes

The examples which used the Vault struct in the vault examples did not initialize a new asset with an empty vault when the vault is deposited to for the first time, this will result in all deposits failing.

Notes

The bug originates because in prior versions of Sway, reads could not fail and would return 0'ed out values for all struct fields, leading to a oversight when updating versions

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.
• I have updated the changelog to reflect the changes on this PR.