dillon1000/react

Revert "[babel] Remove unused PipelineError"

This reverts commit 10d129a8406e9d226abdb6943bf8512e34ce91db 

--- 

Reverts #2311 due to undocumented assumptions being broken. I also added some 
comments to `LoggerEvents` to explain each event type. 

In `Program.ts`, we have something like the following code. `compile` could 
produce any number of errors (not just expected errors / instances of 
`CompilerError`). As an example, we sometimes error in `Codegen` due to babel 
version incompatibilities (`Error: ObjectMethod: Too many arguments passed. 
Received 7 but can receive no more than 5`). 

```js 

try { 

// any error could be thrown here 

compile(input); 

} catch (e) { 

// unknown type for e 

handleError(e, ...); 

} 

```