Refactor image job object, fixed image commands that don't require an existing image

api/IMPLEMENTATION.md

@@ -31,3 +31,18 @@ A client sends *requests* (T-messages) to a server, which subsequently *replies*
 - Twait tag[2] jid[4]
 - Rwait tag[2]
 - Rinit tag[2] max_jobs[2] formats[j]
+
+### Job Object
+The job object is formatted like this:
+```json
+{
+  "cmd": string,      // name of internal image command, e.g. caption
+  "path": string,     // canonical image URL, used for getting the actual image
+  "url": string,      // original image URL, used for message filtering
+  "params": {         // content varies depending on the command, some common parameters are listed here
+    "type": string,   // mime type of output, should usually be the same as input
+    "delay": integer, // for manually specifying GIF frame delay, set to 0 to use the default delay
+    ...
+  }
+}
+```

api/index.js

@@ -241,7 +241,7 @@ const runJob = (job, ws) => {
 
     const object = JSON.parse(job.msg);
     // If the image has a path, it must also have a type
-    if (object.path && !object.type) {
+    if (object.path && !object.params.type) {
       reject(new TypeError("Unknown image type"));
     }