fix(functions/http_content_type): PHP warning when header doesn't exist (GoogleCloudPlatform#1298)

Author: bshaffer

functions/http_content_type/index.php

@@ -23,7 +23,7 @@ function helloContent(ServerRequestInterface $request): string
 {
     $name = 'World';
     $body = $request->getBody()->getContents();
-    switch ($request->getHeader('content-type')[0]) {
+    switch ($request->getHeaderLine('content-type')) {
         // '{"name":"John"}'
         case 'application/json':
           if (!empty($body)) {

functions/slack_slash_command/index.php

@@ -31,13 +31,10 @@ function isValidSlackWebhook(ServerRequestInterface $request): bool
     $SLACK_SECRET = getenv('SLACK_SECRET');
 
     // Check for headers
-    $timestamp = $request->getHeader('X-Slack-Request-Timestamp');
-    $signature = $request->getHeader('X-Slack-Signature');
+    $timestamp = $request->getHeaderLine('X-Slack-Request-Timestamp');
+    $signature = $request->getHeaderLine('X-Slack-Signature');
     if (!$timestamp || !$signature) {
         return false;
-    } else {
-        $timestamp = $timestamp[0];
-        $signature = $signature[0];
     }
 
     // Compute signature