Throw error when conflicting type params are passed

[ljharb]

Per #55 (comment)

An error should be thrown if:

• more than one --type is passed
• any alias for a --type value is passed along with any --type value
• multiple aliases for a --type value are passed

[GeoffreyBooth]

Examples:

node --experimental-modules --type=commonjs --type=module file.js
node --experimental-modules --type=commonjs -m file.js

[devsnek]

getting rid of -m would help so that its more obvious when you've duplicated the flag.

aside from that, node in general just allows duplicated flags.

node --title=1 --title=2
> process.title
'2'

this is particularly important because it means you can override things from NODE_OPTIONS

[ljharb]

@devsnek allowing duplicate flags isn’t necessary to allow overriding; but it may be that node’s options parser lacks the capability to properly distinguish them.

[devsnek]

@ljharb my point is more that this isn't an issue specific to --type (although -m is unique in that its the only short flag which can "disagree" with a longer flag). perhaps someone could raise this issue upstream?

[GeoffreyBooth]

cc @addaleax

[GeoffreyBooth]

Resolved in #45