chore: use nullish coalescing instead of the ternary operator (#4759)

Required by a new ESLint rule.

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[Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

Author: otaviomacedo

packages/jsii-calc/lib/calculator.ts

@@ -301,7 +301,7 @@ export class Calculator extends composition.CompositeOperation {
 
     props = props ?? {};
 
-    const initialValue = props.initialValue ? props.initialValue : 0;
+    const initialValue = props.initialValue ?? 0;
     this.curr = new Number(initialValue);
     this.maxValue = props.maximumValue;
   }