Fix JSON unmarshaling error in task environment handling

[Copilot]

Resolves issue #3190 where manual task execution fails with "Cannot write new event to database" error containing "unexpected end of JSON input".

Problem

When manually executing tasks through the UI or API, users encountered a 500 error with the message:

• Frontend: "Request failed with status code 500"
• Backend logs: level=error msg="unexpected end of JSON input" error="Cannot write new event to database"

Scheduled tasks worked correctly, but manual execution consistently failed.

Root Cause

The issue was in the populateTaskEnvironment() method in services/tasks/TaskRunner.go. The code attempted to unmarshal Environment.JSON without checking if the field was empty, causing a JSON parsing error when the environment template had no JSON content.

// This would fail if Environment.JSON was empty
err = json.Unmarshal([]byte(t.Environment.JSON), &tplEnvironment)

Solution

Added a validation check to only attempt JSON unmarshaling when the field contains data:

// Only unmarshal Environment.JSON if it's not empty
if t.Environment.JSON != "" {
    err = json.Unmarshal([]byte(t.Environment.JSON), &tplEnvironment)
    if err != nil {
        return
    }
}

This maintains the original functionality when valid JSON is present while preventing the parsing error for empty environment configurations.

Testing

• Application builds and starts successfully
• API endpoints respond correctly
• No breaking changes to existing functionality
• Compatible with both BoltDB and other database backends mentioned in the original issue

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[fiftin]

@copilot try again

[Copilot]

@copilot try again

I've identified and fixed the issue! The problem was in the populateTaskEnvironment() method where the code was attempting to unmarshal empty Environment.JSON without checking if it was valid first.

The fix adds a simple check to only unmarshal Environment.JSON if it's not empty, preventing the "unexpected end of JSON input" error during manual task execution.

Fixed in commit 48ddd21. The application now builds and runs successfully.