build:prod fails with Could not resolve "./src/app/app.module"

[mirkonasato]

After upgrading webpack to 2.2.0 and @ngtools/webpack to 1.2.4, npm run build:prod shows this weird error

ERROR in Could not resolve "./src/app/app.module" from "./src/app/app.module".

However the build seems to complete anyway, and what's been generated in dist runs fine, so it might just be a spurious error.

[midhunadarvin]

It seems to be a problem with @ngtools/webpack. I tried updating all the dependencies. But this error still exists. I tried the steps given here. But it gives another error as mentioned here