Fix #11: EACCES on linux and EADDRINUSE

Fixes a brutal crash in case of address 443 or 80 already in use
on the machine and if the script is not runned under sudo on linux.
The script exit, but writing an error message and a tip on how to
resolve.

Update README consequently.

Upgrade minimum node version to 8.

Author: daquinoaldo

.travis.yml

@@ -6,5 +6,5 @@ language: node_js
 node_js:
 - node
 - 10
-- 7.6
+- 8
 after_success: npm run coveralls

README.md

@@ -79,13 +79,19 @@ Checkout the updated list [here](https://github.com/FiloSottile/mkcert/blob/mast
 
 ## Troubleshooting
 ### Node.js version
-https-localhost requires Node.js 7.6 or higher.  
+https-localhost requires Node.js 8 or higher.  
 <sub>If you need compatibility with previously Node.js versions let me know, I'll try to rearrange the code.</sub>
 
 ### root required
 -  **At first run** this tool generate a trusted certificate. The sudo password may be required. If you cannot provide the sudo password generate a `localhost.key` and `localhost.crt` and specify its path with `CERT_PATH=/diractory/containing/certificates/ serve ~/myproj`.
 - **At each run** the password may be required to run the server on port 443 and 80. To avoid the script ask for password specify a different port number: `PORT=4433 serve ~/myproj`.
 
+### EACCES
+Run with sudo to use the default ports 443 and 80. You can also change port with: `PORT=4433 serve ~/myproj`.
+
+### EADDRINUSE
+Another service on your machine is using port 443 or port 80. Stop it or change port with `PORT=4433 serve ~/myproj`.
+
 ### RangeError
 ```
 RangeError: Invalid typed array length: -4095

index.js

@@ -84,5 +84,25 @@ if (require.main === module) {
   if (!process.env.PORT) app.redirect()
 }
 
+/* istanbul ignore next: cannot be tested */
+process.on("uncaughtException", function(err) {
+  switch (err.errno) {
+    case "EACCES":
+      console.error(
+        "EACCES: run as administrator to use the default ports 443 and 80. " +
+        "You can also change port with: `PORT=4433 serve ~/myproj`.")
+      break
+    case "EADDRINUSE":
+      console.error("EADDRINUSE: another service on your machine is using " +
+      "port 443 or port 80.\nStop it or change port with:" +
+      "`PORT=4433 serve ~/myproj`.")
+      break
+    default:
+      console.error("Unexpected error " + err.errno + ":\n\n" + err)
+      break
+  }
+  process.exit(1)
+})
+
 // export as module
 module.exports = createServer