strict tsconfig

package.json

@@ -32,6 +32,7 @@
 	},
 	"devDependencies": {
 		"@release-it/conventional-changelog": "^7.0.2",
+		"@tsconfig/strictest": "^2.0.2",
 		"@types/eslint": "^8.44.3",
 		"@typescript-eslint/eslint-plugin": "^6.7.3",
 		"@typescript-eslint/parser": "^6.7.3",

src/tson.ts

@@ -33,6 +33,10 @@ export function tsonDeserializer(opts: TsonOptions): TsonDeserializeFn {
 
 	for (const handler of opts.types) {
 		if (handler.key) {
+			if (typeByKey[handler.key]) {
+				throw new Error(`Multiple handlers for key ${handler.key} found`);
+			}
+
 			typeByKey[handler.key] =
 				handler as AnyTsonTransformerSerializeDeserialize;
 		}
@@ -42,7 +46,8 @@ export function tsonDeserializer(opts: TsonOptions): TsonDeserializeFn {
 		const walk: WalkFn = (value) => {
 			if (isTsonTuple(value, nonce)) {
 				const [type, serializedValue] = value;
-				const transformer = typeByKey[type];
+				// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+				const transformer = typeByKey[type]!;
 				return transformer.deserialize(walk(serializedValue));
 			}
 

tsconfig.json

@@ -1,16 +1,4 @@
 {
-	"compilerOptions": {
-		"declaration": true,
-		"declarationMap": true,
-		"esModuleInterop": true,
-		"module": "NodeNext",
-		"moduleResolution": "NodeNext",
-		"outDir": "lib",
-		"resolveJsonModule": true,
-		"skipLibCheck": true,
-		"sourceMap": true,
-		"strict": true,
-		"target": "ES2022"
-	},
+	"extends": "@tsconfig/strictest/tsconfig.json",
 	"include": ["src"]
 }