How to Determine the Exact Cause of "tidyParseBuffer" Error

[magicalowl]

Hello, when I use tidyParseBuffer, an error sometimes occurs (the return value is 2).
I tried using a buffer to obtain the error message and got the following information [Note 1]:

Tidy found 5 warnings and 1 error! Not all warnings/errors were shown.

This document has errors that must be fixed before using HTML Tidy to generate a tidied up version.

This is confusing. How could I determine the exact cause of the error?

Here is my environment information:

Tidy version: 5.6.0
OS: Oracle Linux 8.8

Here is the content that caused the tidyParseBuffer error [Note 2]:
<div>\n<div itemprop=\"copy-paste-block\"><span style=\"font-size:14px\">\"</span><a href=\"https://mymbtest-my.sharepoint.com/:v:/g/personal/tzute_mymbtest_onmicrosoft_com/EVQTCMelNmNIgZPSY5G3kgABnDjFzGoK9CyojZ-OQ86ciA\" rel=\"noreferrer noopener\" target=\"_blank\" title=\"https://mymbtest-my.sharepoint.com/:v:/g/personal/tzute_mymbtest_onmicrosoft_com/evqtcmelnmnigzpsy5g3kgabndjfzgok9cyojz-oq86cia\" style=\"font-size:14px\">https://mymbtest-my.sharepoint.com/:v:/g/personal/tzute_mymbtest_onmicrosoft_com/EVQTCMelNmNIgZPSY5G3kgABnDjFzGoK9CyojZ-OQ86ciA</a><span style=\"font-size:14px\">\"</span></div>\n</div><attachment id=\"C7081354-36A5-4863-8193-D26391B79200\"></attachment>

Here is a sample code:

bool HasTag(const char *content, size_t content_size, const char *tag)
{
    bool ret_code = false;
    TidyDoc tdoc = NULL;
    TidyBuffer input_buffer;
    TidyBuffer error_buffer = {0};
    int res = 0;

    tidyBufInit(&input_buffer);

    tdoc = tidyCreate();
    tidyOptSetBool(tdoc, TidyShowWarnings, no);
    tidyOptSetBool(tdoc, TidyShowInfo, no);
    tidyOptSetInt(tdoc, TidyShowErrors, 0);
    tidySetErrorBuffer(tdoc, &error_buffer);

    tidyBufAttach(&input_buffer, (void*)content, content_size);    //[Note 2]

    res = tidyParseBuffer(tdoc, &input_buffer);
    if (res >= 0) {
        res = tidyCleanAndRepair(tdoc);
        if (res >= 0) {
            res = tidyRunDiagnostics(tdoc);
            if (res >= 0) {
                dumpNode(tdoc, tidyGetRoot(tdoc), 0);
                printf("%s\n", error_buffer.bp);    //[Note 1]
            }
        }
    }
    
    // ...

    tidyBufFree(&input_buffer);
    tidyBufFree(&error_buffer);

    return ret_code;
}

If you could provide any suggestions, I would greatly appreciate it.