[feugy]

🖖 What's in there?

Fixes a 500 on malformed Content-Type headers in buffer(), text() and json().

These functions parse the charset with content-type outside of any error handling. A header like Content-Type: application/json; (trailing semicolon) throws a raw TypeError: invalid parameter format, so micro answers with a 500. The fix wraps the parse and throws createError(400, 'Invalid Content-Type header', err), like the existing Invalid JSON and Invalid body errors.

Before	Now
500 Internal Server Error	400 Invalid Content-Type header

This PR targets 9.x, which is new and starts at v9.3.5-canary.3. Services that still use micro@9.3.5-canary.3 can get the fix from a new canary release without moving to 10.x.

🤺 How to test?

curl -i -X POST localhost:3000 -H 'Content-Type: application/json;' -d '{}'

New tests in test/index.js:

• json() returns 400 for application/json;, application/json; charset, application/json;; charset=utf-8 and application.
• text() returns 400 for text/plain;.
• buffer() with an explicit encoding still skips the parse.
• json() still parses a body sent with application/json; charset=utf-8.

Local run on Node 12 with yarn test: lint passes, 66 tests pass. Without the fix, the 5 invalid-header tests fail.

🔬 Notes to reviewers

• 9.x has no CI: the 2019 CircleCI config is not active. I ran the tests locally.
• The nyc coverage report shows Unknown for all files on this branch, also without this change.
• fix: return 400 for malformed Content-Type header #497: same fix for main (10.x).