amplify-cli: Running `amplify api add-graphql-datasource` yields strange error

Before opening, please confirm:

• I have installed the latest version of the Amplify CLI (see above), and confirmed that the issue still persists.
• I have searched for duplicate or closed issues.
• I have read the guide for submitting bug reports.
• I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

How did you install the Amplify CLI?

npm

If applicable, what version of Node.js are you using?

12.22.1

Amplify CLI Version

7.6.2

What operating system are you using?

mac

Amplify Categories

api

Amplify Commands

Not applicable

Describe the bug

Following this instruction set https://docs.amplify.aws/cli-legacy/graphql-transformer/relational/, I follow the instructions to exactness. At the point of running amplify api add-graphql-datasource, I get a strange error. The documentation seems to be legacy(if you look to where the documentation exists), but I failed to find any updated version.

Expected behavior

The amplify command line interface should allow you to run amplify api add-graphql-datasource without error. If that command is deprecated it should state as such.

Reproduction steps

1. Follow the steps in https://docs.amplify.aws/cli-legacy/graphql-transformer/relational/

GraphQL schema(s)

# Put schemas below this line

Log output

🛑 Cannot destructure property 'serviceWalkthroughFilename' of 'serviceMetadata' as it is undefined.
TypeError: Cannot destructure property 'serviceWalkthroughFilename' of 'serviceMetadata' as it is undefined.
    at Object.addDatasource (/usr/local/lib/node_modules/@aws-amplify/cli/node_modules/@aws-amplify/amplify-category-api/src/provider-utils/awscloudformation/index.ts:300:11)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at Object.run (/usr/local/lib/node_modules/@aws-amplify/cli/node_modules/@aws-amplify/amplify-category-api/src/commands/api/add-graphql-datasource.ts:37:21)
    at Object.executeAmplifyCommand (/usr/local/lib/node_modules/@aws-amplify/cli/node_modules/@aws-amplify/amplify-category-api/src/index.ts:222:5)
    at executePluginModuleCommand (/usr/local/lib/node_modules/@aws-amplify/cli/src/execution-manager.ts:204:3)
    at executeCommand (/usr/local/lib/node_modules/@aws-amplify/cli/src/execution-manager.ts:30:5)
    at Object.run (/usr/local/lib/node_modules/@aws-amplify/cli/src/index.ts:205:5)

Additional information

No response