util: fix wrong argument of `ERR_INVALID_MIME_SYNTAX`
Third argument of ERR_INVALID_MIME_SYNTAX is invalid index (not string).
When I tested with below example,
const { MIMEType } = require('node:util');
const myMIME = new MIMEType('text/javascript,');
Before
node:internal/mime:73
throw new ERR_INVALID_MIME_SYNTAX('subtype', str, trimmedSubtype);
^
TypeError [ERR_INVALID_MIME_SYNTAX]: The MIME syntax for a subtype in "text/javascript," is invalid at javascript,
at parseTypeAndSubtype (node:internal/mime:73:11)
at new MIMEType (node:internal/mime:332:18)
After
node:internal/mime:73
throw new ERR_INVALID_MIME_SYNTAX('subtype', str, invalidSubtypeIndex);
^
TypeError [ERR_INVALID_MIME_SYNTAX]: The MIME syntax for a subtype in "text/javascript," is invalid at 10
at parseTypeAndSubtype (node:internal/mime:73:11)
at new MIMEType (node:internal/mime:332:18)