fix: Remove duplicate checks

These were added when setting TypeScript settings to strict,
but should not be needed due to how AsyncHandlers should be used.

src/ldp/http/SimpleRequestParser.ts

@@ -42,9 +42,6 @@ export class SimpleRequestParser extends RequestParser {
     const preferences = await this.preferenceParser.handleSafe(input);
     const body = await this.bodyParser.handleSafe(input);
 
-    if (!input.method) {
-      throw new Error('Missing method.');
-    }
-    return { method: input.method, target, preferences, body };
+    return { method: input.method!, target, preferences, body };
   }
 }

src/ldp/operations/SimplePostOperationHandler.ts

@@ -26,10 +26,7 @@ export class SimplePostOperationHandler extends OperationHandler {
   }
 
   public async handle(input: Operation): Promise<ResponseDescription> {
-    if (!input.body) {
-      throw new UnsupportedHttpError('POST operations require a body.');
-    }
-    const identifier = await this.store.addResource(input.target, input.body);
+    const identifier = await this.store.addResource(input.target, input.body!);
     return { identifier };
   }
 }