Add @typescript-eslint/prefer-nullish-coalescing eslint rule

src/common/parser/ApcParser.ts

@@ -36,9 +36,7 @@ export class ApcParser implements IApcParser {
    * @param handler The handler to register
    */
   public registerHandler(ident: number, handler: IApcHandler): IDisposable {
-    if (this._handlers[ident] === undefined) {
-      this._handlers[ident] = [];
-    }
+    this._handlers[ident] ??= [];
     const handlerList = this._handlers[ident];
     handlerList.push(handler);
     return {

src/common/parser/DcsParser.ts

@@ -29,9 +29,7 @@ export class DcsParser implements IDcsParser {
   }
 
   public registerHandler(ident: number, handler: IDcsHandler): IDisposable {
-    if (this._handlers[ident] === undefined) {
-      this._handlers[ident] = [];
-    }
+    this._handlers[ident] ??= [];
     const handlerList = this._handlers[ident];
     handlerList.push(handler);
     return {

src/common/parser/EscapeSequenceParser.ts

@@ -362,9 +362,7 @@ export class EscapeSequenceParser extends Disposable implements IEscapeSequenceP
 
   public registerEscHandler(id: IFunctionIdentifier, handler: EscHandlerType): IDisposable {
     const ident = this._identifier(id, [0x30, 0x7e]);
-    if (this._escHandlers[ident] === undefined) {
-      this._escHandlers[ident] = [];
-    }
+    this._escHandlers[ident] ??= [];
     const handlerList = this._escHandlers[ident];
     handlerList.push(handler);
     return {
@@ -395,9 +393,7 @@ export class EscapeSequenceParser extends Disposable implements IEscapeSequenceP
 
   public registerCsiHandler(id: IFunctionIdentifier, handler: CsiHandlerType): IDisposable {
     const ident = this._identifier(id);
-    if (this._csiHandlers[ident] === undefined) {
-      this._csiHandlers[ident] = [];
-    }
+    this._csiHandlers[ident] ??= [];
     const handlerList = this._csiHandlers[ident];
     handlerList.push(handler);
     return {

src/common/parser/OscParser.ts

@@ -23,9 +23,7 @@ export class OscParser implements IOscParser {
   };
 
   public registerHandler(ident: number, handler: IOscHandler): IDisposable {
-    if (this._handlers[ident] === undefined) {
-      this._handlers[ident] = [];
-    }
+    this._handlers[ident] ??= [];
     const handlerList = this._handlers[ident];
     handlerList.push(handler);
     return {