lib: inconsistent initial of `expected` in TypeError[ERR_INVALID_ARG_TYPE]

[starkwang]

The initials of expected in TypeError[ERR_INVALID_ARG_TYPE] are inconsistent. Some codes are using uppercase for primitive types and some are using lowercase:

For example, uppercase:
https://github.com/nodejs/node/blob/master/lib/_tls_common.js#L61
https://github.com/nodejs/node/blob/master/lib/internal/child_process.js#L295

Lowercase :
https://github.com/nodejs/node/blob/master/lib/buffer.js#L201
https://github.com/nodejs/node/blob/master/lib/fs.js#L1865

It‘s a little bit of chaos. Should we unify them?

• Version: master
• Platform: all
• Subsystem: internal/errors, lib

[addaleax]

Lowercase array seems like a bug here, thanks for catching that!

Generally, we should try to do the same thing the documentation does; use lowercase for primitive types, uppercase for classes.

[starkwang]

@addaleax What about function? It is not primitive type but we are using 'function'.