Versions 0.12.4+ throw TypeError: Cannot read property 'schema' of undefined

[declension]

Hi
Can't work out quite what's going on but after upgrading from 11.3 -> 12.5 I get this:

  Type Error ---------------------------------------------

  TypeError: Cannot read property 'schema' of undefined
      at new ServerlessPlugin (/home/nick/workspace/HASKELL/sloganator.hs/node_modules/serverless-haskell/dist/index.js:115:35)
      at PluginManager.addPlugin (/home/nick/workspace/HASKELL/sloganator.hs/node_modules/serverless/lib/classes/PluginManager.js:78:28)
      at /home/nick/workspace/HASKELL/sloganator.hs/node_modules/serverless/lib/classes/PluginManager.js:115:31
      at Array.forEach (<anonymous>)
      at PluginManager.loadAllPlugins (/home/nick/workspace/HASKELL/sloganator.hs/node_modules/serverless/lib/classes/PluginManager.js:115:8)
      at /home/nick/workspace/HASKELL/sloganator.hs/node_modules/serverless/lib/Serverless.js:96:35
...etc..

with

Your Environment Information ---------------------------
     Operating System:          linux
     Node Version:              15.2.1
     Framework Version:         1.67.3
     Plugin Version:            3.8.4
     SDK Version:               2.3.2
     Components Version:        2.34.9

After downgrading it seems to stop (this, at least) in 0.12.3 so maybe the schema validation did something? I've checked the docs.

[declension]

A bit of digging - this seems to be the line (from #153), https://github.com/seek-oss/serverless-haskell/pull/153/files#diff-dcdc3e0b3362edb8fec2a51d3fa51f8fb8af8f70247e06d9887fa934834c9122R159 but not sure what it's all doing really

[koterpillar]

Which version of serverless package are you using?

[declension]

Ah yes, I tried a bunch of different ones. Looks like I'm now on a working combo of 1.67.3 and plugin 0.12.3

Previously i had tried upgrading to latest (1.83.2) which I think was the one failing for me as above.

[koterpillar]

Did NPM or Yarn warn you in any way? 0.12.4 bumped the serverless dependency to 2.4.0 (or above). Now that I think of it, it should have mentioned that in a changelog...

[declension]

I don't think it did, but again tried many iterations before realising maybe this wasn't me. I could try to recreate it if that helps?

And yes +1 for mentioning in changelog, I had a look (or a bigger version bump? semver's a bit weird for plugins sometimes IMO)