Ensure optional arrays, arrays with defaults, and strings with defaults are supported (#8896)

Fixing issues with generated ts/js

tests/even_more_defaults.fbs

@@ -0,0 +1,23 @@
+
+enum ABC: int { A, B, C }
+
+struct EvenMoreStruct {
+  g:[int64:2];
+}
+
+table EvenMoreDefaults {
+  str: EvenMoreStruct;
+  ints: [int] = [];
+  floats: [float] = [     ];
+  float_optional: [float];
+  bytes_optional: [ubyte];
+  floats_required: [float] (required);
+  empty_string: string = "";
+  some_string: string = "some";
+  zero_string: string = "0";
+  a_string:string (key);
+  required_string: string (required);
+  abcs: [ABC] = [];
+  bools: [bool] = [];
+  one_bool: bool = true;
+}

tests/ts/TypeScriptTest.py

@@ -87,6 +87,20 @@ flatc(
 )
 esbuild("monster_test.ts", "monster_test_generated.cjs")
 
+flatc(
+    options=[
+        "--ts",
+        "--reflect-names",
+        "--gen-name-strings",
+        "--gen-mutable",
+        "--gen-object-api",
+        "--ts-entry-points",
+        "--ts-flat-files",
+    ],
+    schema="../even_more_defaults.fbs",
+    include="../include_test",
+)
+
 flatc(
     options=["--gen-object-api", "-b"],
     schema="../monster_test.fbs",

tests/ts/my-game/example/monster.ts

@@ -81,11 +81,11 @@ mutate_hp(value:number):boolean {
   return true;
 }
 
-name():string|null
-name(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
-name(optionalEncoding?:any):string|Uint8Array|null {
+name():string
+name(optionalEncoding:flatbuffers.Encoding):string|Uint8Array
+name(optionalEncoding?:any):string|Uint8Array {
   const offset = this.bb!.__offset(this.bb_pos, 10);
-  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+  return this.bb!.__string(this.bb_pos + offset, optionalEncoding);
 }
 
 inventory(index: number):number|null {