Improve error handling in GhCliApiClient

[hossain-khan]

Problem

Currently, GhCliApiClient.executeCommand() throws a generic RuntimeException for all errors:

if (exitCode != 0) {
    throw RuntimeException("gh command failed with exit code $exitCode: $output")
}

This doesn't distinguish between:

• GitHub CLI not installed
• Not authenticated (gh auth login needed)
• GitHub API errors (rate limit, not found, etc.)
• Network connectivity issues

Proposed Solution

1. Parse GH CLI error output to identify specific error types
2. Create custom exceptions for different error scenarios:
   • GhCliNotAuthenticatedException
   • GhCliRateLimitException
   • GhCliNetworkException
3. Map to existing error handling via ErrorProcessor
4. Provide actionable error messages to users

Example:

private fun executeCommand(command: List<String>): String {
    val process = ProcessBuilder(command).redirectErrorStream(true).start()
    val output = BufferedReader(InputStreamReader(process.inputStream)).use { it.readText() }
    val exitCode = process.waitFor()
    
    if (exitCode != 0) {
        when {
            output.contains("authentication") || output.contains("not logged in") ->
                throw IllegalStateException("GitHub CLI not authenticated. Run: gh auth login")
            output.contains("rate limit") ->
                throw RuntimeException("GitHub API rate limit exceeded: $output")
            output.contains("not found") ->
                throw RuntimeException("Resource not found: $output")
            else ->
                throw RuntimeException("gh command failed with exit code $exitCode: $output")
        }
    }
    return output
}

Benefits

• Better user experience with actionable error messages
• Easier troubleshooting
• Consistent error handling with Retrofit implementation
• Graceful handling of authentication issues

Priority

High - Improves user experience significantly

Related Files

• src/main/kotlin/dev/hossain/githubstats/client/GhCliApiClient.kt
• src/main/kotlin/dev/hossain/githubstats/util/ErrorProcessor.kt