Log identity meta unmarshalling errors instead of returning them

[coderabbitai]

Problem

Currently, when unmarshalling identity meta fails in various API handlers, the error is returned and blocks the entire request. This behavior should be changed to just log the error and continue processing the request.

Context

This was identified during the review of PR #4145, specifically in the discussion at #4145 (comment)

Multiple handlers exhibit this pattern where db.UnmarshalNullableJSONTo errors for identity meta are returned rather than logged:

• go/apps/api/routes/v2_keys_verify_key/handler.go
• go/apps/api/routes/v2_keys_whoami/handler.go
• go/apps/api/routes/v2_apis_list_keys/handler.go
• go/apps/api/routes/v2_keys_get_key/handler.go

Expected Behavior

When identity meta unmarshalling fails, the error should be logged and the request should continue without blocking. The meta field can be left nil/unset in the response.

References

• PR: refactor: make unmarshalling easier and override json to RawMessage #4145
• Discussion: refactor: make unmarshalling easier and override json to RawMessage #4145 (comment)
• Requested by: @ogzhanolguncu

[linear]

ENG-2176