fix(sdk): improve buyer error tips

[xuelianhan007]

Description

Made some improvements to the error tips for creating the buyer.

Related Issue

#187

Motivation and Context

How This Has Been Tested

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring or add test (improvements in base code or adds test coverage to functionality)
• CI/CD or documentation update (changes to CI/CD pipeline or documentation)

Checklist

• I ensured that the documentation is up to date
• I explained why this PR updates in detail with reasoning why it's required
• I would like a code coverage CI quality gate exception and have explained why

[github-actions]

Library Vulnerability scan results

The following vulnerabilities have been found in libraries included in the repository (some might be dependencies of dependencies).

Critical 🔴 and High 🟡 severity vulnerabilities must be fixed before the PR can be merged, even if they are dependencies of dependencies.

Library	Vulnerable version	Severity	Fix version	Vulnerability ID

[kuangxiang20240501]

LGTM

[sonarqubecloud]

Quality Gate passed for 'kraken_nodejs'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarqubecloud]

Quality Gate passed for 'kraken_java'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[zhiyaoPCCW]

LGTM