[TC-ACE-2.1][TC-IDM-2.2] Issue when reading ThreadNetworkDiagnostics.Attributes.RouteTable on endpoint 2

[Martin-NXP]

Test issue(s)

Failure identify with tests:
1.TC-ACE-2.1
2.TC-IDM-2.2

Error logs (TC-ACE-2.1):
Problem: ProblemSeverity.ERROR
test_name: Read access Checker - 1
location:
Endpoint: 2,
Cluster: 53 (0x35) ThreadNetworkDiagnostics
Attribute:8 (0x08)
problem: Error reading <class 'chip.clusters.Objects.ThreadNetworkDiagnostics'>:<class 'chip.clusters.Objects.ThreadNetworkDiagnostics.Attributes.RouteTable'> = ValueDecodeFailure(TLVValue=None, Reason=InteractionModelError(<Status.Failure: 1>))
spec_location:

[MatterTest] 12-13 07:33:24.218 INFO
Problem: ProblemSeverity.ERROR
test_name: Read access Checker - 2
location:
Endpoint: 2,
Cluster: 53 (0x35) ThreadNetworkDiagnostics
Attribute:8 (0x08)
problem: Error reading <class 'chip.clusters.Objects.ThreadNetworkDiagnostics'>:<class 'chip.clusters.Objects.ThreadNetworkDiagnostics.Attributes.RouteTable'> = ValueDecodeFailure(TLVValue=None, Reason=InteractionModelError(<Status.Failure: 1>))
spec_location:

[MatterTest] 12-13 07:33:24.219 INFO
Problem: ProblemSeverity.ERROR
test_name: Read access Checker - 3
location:
Endpoint: 2,
Cluster: 53 (0x35) ThreadNetworkDiagnostics
Attribute:8 (0x08)
problem: Error reading <class 'chip.clusters.Objects.ThreadNetworkDiagnostics'>:<class 'chip.clusters.Objects.ThreadNetworkDiagnostics.Attributes.RouteTable'> = ValueDecodeFailure(TLVValue=None, Reason=InteractionModelError(<Status.Failure: 1>))
spec_location:

[MatterTest] 12-13 07:33:24.219 INFO
Problem: ProblemSeverity.ERROR
test_name: Read access Checker - 4
location:
Endpoint: 2,
Cluster: 53 (0x35) ThreadNetworkDiagnostics
Attribute:8 (0x08)
problem: Error reading <class 'chip.clusters.Objects.ThreadNetworkDiagnostics'>:<class 'chip.clusters.Objects.ThreadNetworkDiagnostics.Attributes.RouteTable'> = ValueDecodeFailure(TLVValue=None, Reason=InteractionModelError(<Status.Failure: 1>))
spec_location:

[MatterTest] 12-13 07:33:24.220 INFO
Problem: ProblemSeverity.ERROR
test_name: Read access Checker - 5
location:
Endpoint: 2,
Cluster: 49 (0x31) NetworkCommissioning
Attribute:1 (0x01)
problem: Error reading <class 'chip.clusters.Objects.NetworkCommissioning'>:<class 'chip.clusters.Objects.NetworkCommissioning.Attributes.Networks'> = ValueDecodeFailure(TLVValue=None, Reason=InteractionModelError(<Status.Failure: 1>))
spec_location:

[MatterTest] 12-13 07:33:24.220 INFO
Problem: ProblemSeverity.ERROR
test_name: Read access Checker - 5
location:
Endpoint: 2,
Cluster: 53 (0x35) ThreadNetworkDiagnostics
Attribute:8 (0x08)
problem: Error reading <class 'chip.clusters.Objects.ThreadNetworkDiagnostics'>:<class 'chip.clusters.Objects.ThreadNetworkDiagnostics.Attributes.RouteTable'> = ValueDecodeFailure(TLVValue=None, Reason=InteractionModelError(<Status.Failure: 1>))
spec_location:

Context:
NXP Thermostat application with OTBR support (examples/thermostat/nxp/zap/thermostat_matter_br.zap) with wifi network commissioning on endpoint 0 and Thread network commissioning on endpoint 2. Thread network is not started by default.

The issue could be reproduce manually:
1/ Run Wifi commissioning (pass)
2/ Read ThreadNetworkDiagnostics.Attributes.RouteTable (./chip-tool threadnetworkdiagnostics read route-table 1 2)
chip-tool error:
[TOO] Run command failure: IM Error 0x00000501: General error: 0x01 (FAILURE)

Observation:
As the Thread network is not started, there is not Thread route, an error is return here:
https://github.com/project-chip/connectedhomeip/blob/master/src/app/clusters/thread-network-diagnostics-server/thread-network-diagnostics-provider.cpp#L275C20-L275C27

Questions
1/ Is it normal to return an error if there no Thread route ?
2/ If yes, should tests prerequisite should be updated in order to start the Thread network before reading attributes ?

Platform

No response

Anything else?

No response