"Cannot resolve module" error could be more helpful

If this is a bug, please try reproducing using https://flow.org/try/.

As a first-time user of Flow, wasted a lot of time trying to figure out how to fix that error - when it turned out that all it means is that you need to install a type definition for the module. I thought it was having issues finding or importing the module itself.

Suggestion: "Cannot resolve module X. The module may not have typing definitions, which can be installed using flow-typed."