Unresolvable FEEL expression resolving as `null` with `Null` type

[barinali]

Describe the Bug

As reported by @nikku in bpmn-io/variable-outline#24 (comment), we are displaying some variables' resolved values and types wrong.

With the following ioMapping declaration, I think we should have resolved agentContext as Any with =agent.context rather than null with Null type.

<zeebe:ioMapping>
  <zeebe:input source="=agent.context" target="agentContext" />
  <zeebe:output source="=agent" target="agent" />
</zeebe:ioMapping>

The variables are resolved as below from variable-resolver.

[
  {
    "name": "agentContext",
    "type": "Null",
    "info": "",
    "entries": [],
    "detail": "Null"
  },
  {
    "name": "agent",
    "provider": [
      null
    ],
    "type": "Any",
    "info": "=agent",
    "entries": [ ],
    "detail": "Any"
  }
]

Steps to Reproduce

1. Open this diagram
2. Focus on AI Agent ad-hoc subprocess
3. Inspect agent and agentContext variables in the new variables panel or VariableResolver#getVariables
4. While agent is =agent, agentContext is null

Expected Behavior

1. agentContext should have been typed as Any with =agent.context value as it cannot be resolved

Environment

• Library version: 2.0.0

[barinali]

@nikku created this issue as a follow-up on this remark. agentContext seems misresolved and hence, variable-outline renders it as you reported.