dev: enable sourceMaps for better debugging experience

[pranshuchittora]

Description

Trying to discuss the need for sourceMaps for better debugging.

Current behaviour

The build doesn't generate any source maps as of now (correct me if I am wrong).
Hence it's very hard to debug code using breakpoints.

Expected behaviour

Enabling source maps to enable synchronisation of the breakpoints between the source files & build files.

Suggested Approach

Enabling "sourceMaps": "inline" in the babelrc to enable source maps.
But the build size has been increased significantly
(Source maps enabled)

     *.js x135 | 1908.47 KB
    *.mjs x135 | 1868.78 KB
*.js.flow x135 |  561.75 KB
   *.d.ts x106 |  152.89 KB
     README.md |    5.36 KB
       LICENSE |    1.05 KB
  package.json |    0.61 KB
---------------------------
         Total |    4.39 MB

(Original build size without source maps)

     *.js x135 | 600.55 KB
*.js.flow x135 | 561.75 KB
    *.mjs x135 | 517.53 KB
   *.d.ts x106 | 152.89 KB
     README.md |   5.36 KB
       LICENSE |   1.05 KB
  package.json |   0.61 KB
--------------------------
         Total |   1.80 MB

This issue can be solved by providing an interface to create two builds i.e. prod (the one without source maps) & dev (the one with source maps)

Future prospects

After migrating to TS #2104 the approach can be different.