not able to build or install

localonly@ubuntu:~/opensource.builders$ yarn install
yarn install v1.22.10
[1/4] Resolving packages...
success Already up-to-date.
Done in 1.20s.
localonly@ubuntu:~/opensource.builders$
localonly@ubuntu:~/opensource.builders$
localonly@ubuntu:~/opensource.builders$ yarn start
yarn run v1.22.10
$ gatsby develop
success open and validate gatsby-configs - 0.112s
success load plugins - 1.362s
success onPreInit - 0.053s
success initialize cache - 0.009s
success copy gatsby files - 0.149s
success onPreBootstrap - 0.031s
success createSchemaCustomization - 0.052s
success Checking for changed pages - 0.002s
success source and transform nodes - 0.142s
success building schema - 0.480s

ERROR #11321 PLUGIN

"gatsby-node.js" threw an error while running the createPages lifecycle:

Cannot read property 'map' of undefined

8 | const compTemplate = path.resolve(`./src/templates/comparisons.js`)
9 | altsData.alternatives.forEach((comp_object) => {
> 10 | comp_object.commercial.map((object) => {
| ^
11 | var path = object.main.replace(/\s+/g, "-").toLowerCase()
12 | createPage({
13 | path,

File: gatsby-node.js:10:28

TypeError: Cannot read property 'map' of undefined

- gatsby-node.js:10
/home/localonly/opensource.builders/gatsby-node.js:10:28