When application->fqdn is null, COOLIFY_FQDN and COOLIFY_URL are set to null.
These null values cause nixpacks to fail parsing the config with
"invalid type: null, expected a string".
Filter out null and empty string values when generating environment variables
for the nixpacks plan JSON. Fixes#6830.
Filter out null and empty environment variables when generating Nixpacks build
configuration to prevent JSON parsing errors. Environment variables with null or
empty values were being passed as `--env KEY=` which created invalid JSON with
null values, causing deployment failures.
This fix ensures only valid non-empty environment variables are included in both
user-defined and auto-generated COOLIFY_* environment variables.
🤖 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>
