fix: throw explicit error when KeyringController is locked

[mikesposito]

Blocked by:

• chore: fix lint warnings in KeyringController #5170

Explanation

No specific error is thrown when an operation that requires an unlocked vault is attempted while KeyringController.state.isUnlocked is false. This doesn't make the operations possible, but it doesn't give a clear error message either.

This PR adds an assertion on almost all KeyringController methods to check if the controller is unlocked and to throw an error when it isn't.

References

• Fixes [KeyringController] No specific error is thrown when the controller is locked #5171

Changelog

@metamask/keyring-controller

• CHANGED: A specific error message is thrown when any operation is attempted while the controller is locked

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've highlighted breaking changes using the "BREAKING" category above as appropriate
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes