Current behavior:

When running func deploy or func build with both --image and --registry flags that specify different registries, the command proceeds to build instead of validating the conflict:

rayyan@rayyan-seliya:/mnt/c/Users/RAYYAN/Desktop/func/myfunction$ func deploy --image ghcr.io/user/func:latest --registry different-registry.com/user
Building function image
^CError: failed to fetch builder image 'ghcr.io/knative/builder-jammy-tiny:latest': context canceled

This forces users to:

1. Wait through the entire build process before realizing the conflict
2. Manually cancel (Ctrl+C) to stop the misleading build
3. Guess what went wrong from a generic "failed to fetch builder image" error
4. Not understand that the issue is with conflicting registry specifications

Proposed improvement:

Provide immediate validation and clear guidance when image and registry flags conflict:

Error: conflicting image and registry options

You cannot use both --image and --registry together when they specify different registries.

These are two different ways to specify where to push your function image.

Choose ONE of these approaches:

1. Use --image to specify the complete image name:
   func deploy --image <full-image-name>

2. Use --registry and let the system create the image name automatically:
   func deploy --registry <registry>

For more options, run 'func deploy --help'

For func build:

Error: conflicting image and registry options

You cannot use both --image and --registry together when they specify different registries.

These are two different ways to specify where to push your function image.

Choose ONE of these approaches:

1. Use --image to specify the complete image name:
   func build --image <full-image-name>

2. Use --registry and let the system create the image name automatically:
   func build --registry <registry>

For more options, run 'func build --help'

Solution:
Implement a 2-layer error system:

• Layer 1 (Technical): Return ErrConflictingImageAndRegistry from validation in pkg/functions/errors.go
• Layer 2 (CLI): Catch the error in cmd/build.go and cmd/deploy.go and provide user-friendly guidance

Expected Workflow:

The validation should occur before any build attempts:

1. Parse command flags
2. Validate flag combinations for conflicts
3. Return clear error if conflicts detected
4. Only proceed to build if validation passes

Compatibility Notes:

The validation should allow compatible combinations:

• ✅ --registry example.com/alice --image example.com/alice/subnamespace/myfunc (subnamespace)
• ✅ --registry example.com/alice --image example.com/alice/func:latest (exact match)
• ❌ --registry example.com/alice --image different.com/user/func (different registry)

User Impact:

• Current: Confusing build failure → time wasted waiting → need to investigate → unclear error message
• Improved: Immediate validation → clear error explanation → actionable guidance → better developer experience