[202012] Check for adding default vlan attempt added (#2075)

[puffc]

fixing https://github.com/sonic-net/sonic-buildimage/issues/9946 *CLI throws an error specifying the user that Vlan 1 is default VLAN. Fix Orchagent crash.

Signed-off-by: Julian Chang - TW [email protected]

What I did

BACKPORT OF: #2075

How I did it

How to verify it

config vlan add 1 CLI throws an error specifying the user that Vlan 1 is default VLAN. Orchagent doesn't crash.

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[linux-foundation-easycla[bot]]

• :x: - login: @MaratGubaiev / name: Marat Gubaiev . The commit (c1f8e8bf82bf134f7176f4dc51425b0186bcef56) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.

[puffc]

/easycla

[puffc]

Close this PR due to ICLA issue.