Adds proper error return to stuff involving upload links

src/operations/video_upload.gql

@@ -6,20 +6,57 @@ mutation CreateUploadStream($videoMetadataInput: VideoMetadataInput!) {
 
 mutation GetUploadLink($videoId: Int!, $segmentIndex: Int!) {
   getUploadLink(videoId: $videoId, segmentIndex: $segmentIndex) {
-    uploadUrl
-    headers {
-      key
-      value
+    value {
+      ... on UploadLink {
+        uploadUrl
+        headers {
+          key
+          value
+        }
+      }
+      ... on GetUploadLinkErrors {
+        error {
+          ... on MustHaveSetForUploadLinkErr {
+            resolution
+            framesPerSecond
+          }
+          ... on SegmentAlreadyUploadedErr {
+            segmentId
+          }
+          ... on ProcessingFailedErr {
+            processing {
+              status
+              errors {
+                message
+              }
+            }
+          }
+        }
+      }
+    }
+    stream {
+      uploadCompletionCursor
     }
   }
 }
 
 mutation GetHlsInitUploadLink($videoId: Int!) {
   getHlsInitUploadLink(videoId: $videoId) {
-    uploadUrl
-    headers {
-      key
-      value
+    value {
+      ... on UploadLink {
+        uploadUrl
+        headers {
+          key
+          value
+        }
+      }
+      ... on GetUploadLinkErrors {
+        error {
+          ... on NoInitForChunkedUploadErr {
+            segmentType
+          }
+        }
+      }
     }
   }
 }