fix: user Array.isArray() for more reliable array check

Fix critical bugs and anti-patterns: parameter reassignment, unsafe non-null assertions, and unclear type checks

Author: streamich

src/json-crdt-patch/codec/binary/Decoder.ts

@@ -49,7 +49,7 @@ export class Decoder extends CborDecoder<CrdtReader> {
     this.patchSid = clock.sid;
     const builder = (this.builder = new PatchBuilder(clock));
     const map = this.val();
-    if (map instanceof Array) builder.patch.meta = map[0];
+    if (Array.isArray(map)) builder.patch.meta = map[0];
     this.decodeOperations();
     return builder.patch;
   }

src/json-crdt-patch/codec/compact/encode.ts

@@ -12,7 +12,7 @@ const timestamp = (sid: number, ts: ITimestampStruct): types.CompactCodecTimesta
 
 const timespan = (sid: number, span: ITimespanStruct): types.CompactCodecTimespan => {
   const ts = timestamp(sid, span);
-  if (ts instanceof Array) {
+  if (Array.isArray(ts)) {
     ts.push(span.span);
     return ts;
   }

src/json-crdt/json-patch/JsonPatch.ts

@@ -160,7 +160,7 @@ export class JsonPatch<N extends JsonNode = JsonNode<any>> {
     if (!(node instanceof StrNode)) throw new Error('NOT_FOUND');
     const length = node.length();
     if (length <= pos) return;
-    const deletionLength = Math.min(len ?? str!.length, length - pos);
+    const deletionLength = Math.min(len ?? str.length, length - pos);
     const range = node.findInterval(pos, deletionLength);
     if (!range) throw new Error('OUT_OF_BOUNDS');
     this.builder().del(node.id, range);

src/json-size/msgpackSizeFast.ts

@@ -34,7 +34,7 @@ export const msgpackSizeFast = (value: unknown): number => {
     case 'boolean':
       return 1;
   }
-  if (value instanceof Array) return arraySize(value);
+  if (Array.isArray(value)) return arraySize(value);
   if (isUint8Array(value)) return 5 + value.length;
   if (value instanceof JsonPackValue) return (value as JsonPackValue).val.length;
   if (value instanceof JsonPackExtension) return 6 + (value as JsonPackExtension).val.length;

src/json-text/toTree.ts

@@ -4,14 +4,14 @@ import {stringify} from './stringify';
 const isPrimitive = (value: unknown): boolean => typeof value !== 'object' || value === null;
 const isOneLineValue = (value: unknown): boolean => {
   if (isPrimitive(value)) return true;
-  if (value instanceof Array && !value.length) return true;
+  if (Array.isArray(value) && !value.length) return true;
   if (value && typeof value === 'object' && !Object.keys(value).length) return true;
   return false;
 };
 const isSimpleString = (str: string) => /^[a-z0-9]+$/i.test(str);
 
 export const toTree = (value: unknown, tab: string = ''): string => {
-  if (value instanceof Array) {
+  if (Array.isArray(value)) {
     if (value.length === 0) return '[]';
     return printTree(
       tab,