improve condition to check if the value or the default value of a cir…

…cuit input is provided in the circuit input parser; Simplify calculateStringCharCodeSum call in case of string type

examples/bri-3/src/bri/zeroKnowledgeProof/services/circuit/circuitInputsParser/circuitInputParser.service.ts

@@ -17,7 +17,7 @@ export class CircuitInputsParserService {
           mapping.payloadJsonPath,
         );
 
-        if (!value && !mapping.defaultValue) {
+        if (value === undefined && mapping.defaultValue === undefined) {
           this.logger.logError(
             `Missing value and default value for mapping ${cim.mapping} while mapping circuit inputs for payload ${payload}`,
           );
@@ -26,9 +26,7 @@ export class CircuitInputsParserService {
 
         switch (mapping.dataType) {
           case 'string':
-            result[mapping.circuitInput] = value
-              ? this.calculateStringCharCodeSum(value)
-              : this.calculateStringCharCodeSum(mapping.defaultValue);
+            result[mapping.circuitInput] = this.calculateStringCharCodeSum(value || mapping.defaultValue);
             break;
 
           case 'integer':