fix: prevents fastify-compress from trying to work with something it cannot

Sending something other than buffers of strings in the `payload` happens, but this would break the later `Buffer.byteLength(payload)`

Signed-off-by: Bart Riepe <bart@serial-experiments.com>

Author: Aeolun

index.js

@@ -272,6 +272,11 @@ function buildRouteCompress (_fastify, params, routeOptions, decorateOnly) {
       return next(null, payload)
     }
 
+    // Don't compress uncompressable things
+    if (!Buffer.isBuffer(payload) && typeof payload !== "string") {
+      return next(null, payload);
+    }
+    
     if (typeof payload.pipe !== 'function') {
       if (Buffer.byteLength(payload) < params.threshold) {
         return next()