refactoring: handled possible memory allocation errors in both convert functions

src/conversionOfNumbers/conversionOfNumbers.c

@@ -24,6 +24,7 @@ char* convertIntToBinaryStr(int input){
     int length = binaryStrLen(input);
     int rest;
     char* result = (char*)malloc(sizeof(char) * length + 1);
+    if(result == NULL) return NULL;
     if(input < 0){
         result[0] = '-';
         input *= -1;
@@ -67,6 +68,7 @@ char* convertIntToHex(int input){
     int length = hexStrLen(input);
     int rest;
     char* result = (char*)malloc(sizeof(char) * length + 1);
+    if(result == NULL) return NULL;
     result[length] = '\0';
     do{
         rest = input % 16;