diff --git a/core/core-client.ts b/core/core-client.ts
index a8f2755..6fe7d4a 100644
--- a/core/core-client.ts
+++ b/core/core-client.ts
@@ -6,6 +6,7 @@ import b64 from 'base64-js'
 //types
 import type { id, PropKey, PropValue, CoreMessageKind, ClientMessageKind, Bit } from './types.js'
 import type { RateLimit } from './ratelimit.js'
+import type { SocioFiles } from './types.js';
 type MessageDataObj = { id: id, verb?: string, table?: string, status?:string, result?:string|object|boolean|PropValue, prop?:PropKey, data?:object };
 type SubscribeCallbackObjectSuccess = ((res: object | object[]) => void) | null;
 type SubscribeCallbackObject = { success: SubscribeCallbackObjectSuccess, error?: Function};
@@ -145,12 +146,11 @@ export class SocioClient extends LogHandler {
                     }else throw new E('Not enough prop info sent from server to perform prop update.', data)
                     break;
                 case 'CMD': if(this.lifecycle_hooks?.cmd) this.lifecycle_hooks.cmd(data?.data); break; //the server pushed some data to this client, let the dev handle it
-                case 'ERR'://when using this, make sure that the setup query is a promise func. The result field is used as a cause of error msg on the backend
-                    this.#FindID(kind, data?.id);
+                case 'ERR'://The result field is sometimes used as a cause of error msg on the backend
                     if (typeof this.#queries[data.id] == 'function')
-                        (this.#queries[data.id] as Function)(null);
-                    
-                    throw new E(`Request to Server returned ERROR response for query id, reason #[err-msg-kind]`, data.id, data?.result as Bit);
+                        (this.#queries[data.id] as Function)();
+
+                    this.HandleError(new E(`Request to Server returned ERROR response for query id, reason #[err-msg-kind]`, data?.id, data?.result as Bit))
                 case 'RECON': 
                     this.#FindID(kind, data?.id);
                     //@ts-expect-error
@@ -169,7 +169,27 @@ export class SocioClient extends LogHandler {
         this.#ws?.send(JSON.stringify(Object.assign({}, { kind, data:data[0] }, ...data.slice(1))));
         this.HandleInfo('sent:', kind, data);
     }
-    SendBlob(blob: Blob | ArrayBuffer | ArrayBufferView){
+    async SendFiles(files:File[], other_data:object|undefined={}){
+        const proc_files: SocioFiles = {}; //my own kind of FormData, specific for files, because FormData is actually a very riggid type
+
+        //add each file
+        for(const file of files){
+            //relevant info about files is stored in file_meta
+            const file_meta = {
+                lastModified: file.lastModified,
+                size: file.size,
+                type: file.type
+            };
+            proc_files[file.name] = { file_meta, bin: b64.fromByteArray(new Uint8Array(await file.arrayBuffer()))}; //this is the best way that i could find. JS is really unhappy about binary data
+        }
+
+        //create the server request as usual
+        const {id, prom} = this.CreateQueryPromise();
+        this.Send('FILES', { id, files:proc_files, other_data});
+
+        return prom;
+    }
+    SendBinary(blob: Blob | ArrayBuffer | ArrayBufferView) { //send binary. Unfortunately, it is not useful for me to invent my own byte formats and build functionality. You can tho. This is just low level access.
         if (this.#queries[`BLOB`]) throw new E('BLOB already being uploaded. Wait until the last query completes!');
 
         this.#ws?.send(blob);
@@ -179,25 +199,6 @@ export class SocioClient extends LogHandler {
             this.#queries[`BLOB`] = res
         });
     }
-    async SendFiles(files:File[]){
-        if (this.#queries[`FILES`]) throw new E('FILES already being uploaded. Wait until the last query completes!');
-
-        const proc_files = {};
-
-        for(const file of files){
-            const file_meta = {
-                lastModified: file.lastModified,
-                size: file.size,
-                type: file.type
-            };
-            proc_files[file.name] = { file_meta, bin: b64.fromByteArray(new Uint8Array(await file.arrayBuffer()))};
-        }
-
-        const {id, prom} = this.CreateQueryPromise();
-        this.Send('FILES', { id:id, files:proc_files});
-
-        return prom;
-    }
     CreateQueryPromise(){
         const id = this.GenKey;
         const prom = new Promise((res) => {
@@ -361,10 +362,10 @@ export class SocioClient extends LogHandler {
             return SocioClient.#key
         }
     }
-    //checks if the ID of a query exists (i.e. has been registered), otherwise rejects and logs
+    //checks if the ID of a query exists, otherwise rejects and logs
     #FindID(kind: string, id: id) {
         if (!(id in this.#queries))
-            throw new E(`${kind} message for unregistered SQL query! msg_id -`, id, Object.keys(this.#queries))
+            throw new E(`${kind} message for unregistered SQL query! msg_id -`, id);
     }
     #HandleBasicPromiseMessage(kind:string, data:MessageDataObj){
         this.#FindID(kind, data?.id);
diff --git a/core/fs-utils.ts b/core/fs-utils.ts
index f1d1385..0418b1e 100644
--- a/core/fs-utils.ts
+++ b/core/fs-utils.ts
@@ -1,9 +1,9 @@
 import fs from 'fs';
 import b64 from 'base64-js'
 import { default as os_path } from "path";
-// import { log } from './logging.js';
 
-export type SocioFiles = {[filename:string]:{file_meta:{}, bin:string}};
+//types
+import type { SocioFiles } from './types.js';
 
 export async function SaveFilesToDiskPath(path_array: string[], files: SocioFiles){
     for (const [filename, file_data] of Object.entries(files)) {
diff --git a/core/types.d.ts b/core/types.d.ts
index 22b6d0f..1e46601 100644
--- a/core/types.d.ts
+++ b/core/types.d.ts
@@ -1,12 +1,16 @@
+//general types
 export type id = string | number;
 export type Bit = 0 | 1;
 
+//props
 export type PropKey = string;
 export type PropValue = object | string | number | null;
 export type PropAssigner = (key: PropKey, new_val:PropValue) => boolean;
 
+//misc
+export type SocioFiles = {[filename: string]: {file_meta: {lastModified: number, size: number, type: string}, bin: string } }; //bin is a base64 string of the bytes of the raw file
+export type QueryMarker = 'socio' | 'auth' | 'perm';
+
 //msg kinds
 export type CoreMessageKind = 'SUB' | 'UNSUB' | 'SQL' | 'PING' | 'AUTH' | 'GET_PERM' | 'PROP_SUB' | 'PROP_UNSUB' | 'PROP_GET' | 'PROP_SET' | 'SERV' | 'ADMIN' | 'RECON' | 'FILES';
-export type ClientMessageKind = 'CON' | 'UPD' | 'PONG' | 'AUTH' | 'GET_PERM' | 'RES' | 'ERR' | 'PROP_UPD' | 'CMD' | 'RECON';
-
-export type QueryMarker = 'socio' | 'auth' | 'perm';
\ No newline at end of file
+export type ClientMessageKind = 'CON' | 'UPD' | 'PONG' | 'AUTH' | 'GET_PERM' | 'RES' | 'ERR' | 'PROP_UPD' | 'CMD' | 'RECON';
\ No newline at end of file