clarify errors

* use macros for logic errors, not input errors
* throw on parsing failure in `operator>>()`, not assert
* throw on malloc, not assert

src/lib_json/json_reader.cpp

@@ -1994,7 +1994,7 @@ std::istream& operator>>(std::istream& sin, Value& root) {
             "Error from reader: %s",
             errs.c_str());
 
-    JSON_FAIL_MESSAGE("reader error");
+    throw std::runtime_error("reader error");
   }
   return sin;
 }

src/lib_json/json_value.cpp

@@ -87,9 +87,11 @@ static inline char* duplicateStringValue(const char* value,
     length = Value::maxInt - 1;
 
   char* newString = static_cast<char*>(malloc(length + 1));
-  JSON_ASSERT_MESSAGE(newString != 0,
-                      "in Json::Value::duplicateStringValue(): "
-                      "Failed to allocate string value buffer");
+  if (newString == NULL) {
+    throw std::runtime_error(
+        "in Json::Value::duplicateStringValue(): "
+        "Failed to allocate string value buffer");
+  }
   memcpy(newString, value, length);
   newString[length] = 0;
   return newString;
@@ -108,9 +110,11 @@ static inline char* duplicateAndPrefixStringValue(
                       "length too big for prefixing");
   unsigned actualLength = length + sizeof(unsigned) + 1U;
   char* newString = static_cast<char*>(malloc(actualLength));
-  JSON_ASSERT_MESSAGE(newString != 0,
-                      "in Json::Value::duplicateAndPrefixStringValue(): "
-                      "Failed to allocate string value buffer");
+  if (newString == 0) {
+    throw std::runtime_error(
+        "in Json::Value::duplicateAndPrefixStringValue(): "
+        "Failed to allocate string value buffer");
+  }
   *reinterpret_cast<unsigned*>(newString) = length;
   memcpy(newString + sizeof(unsigned), value, length);
   newString[actualLength - 1U] = 0; // to avoid buffer over-run accidents by users later