bit link should not run if there are no dists present

[odedre]

Describe the bug

if I run the command bit link without building first, and there are no dists present, bit should indicate this with an error.

Steps to Reproduce

1. import a compiler
2. create a component
3. run bit add
4. run bit link
5. bit creates links that point to an empty folder

Expected Behavior

either:

bit should indicate with warning that there are no dists present and the links that were created might be wrong

or:

bit link should not run and throw error instead

Specifications

• Bit version: 14.7.4
• Node version: v10.15.3
• yarn version: 1.13.0
• Platform: macos
• Bit compiler (include version): bit.envs/compilers/react-typescript@3.1.43

[davidfirst]

In the next major version (Harmony), the links will be different, they might point to the capsules or to the source inside the workspace. Probably not to the dists.