用长度和结束标记读取R中的XML数据问题

我得到了一个行内XML数据表，如下所示：

尝试读取一行XML时，出现以下错误：

> ax1 <- xmlParse(a1$FILE_DATA[[1]], asText = TRUE)
Premature end of data in tag PDFREPORT1 line 3
Premature end of data in tag PDFREPORT line 3
Premature end of data in tag PDFREPORTs line 3
Premature end of data in tag REPORT line 1
Error: 1: Premature end of data in tag PDFREPORT1 line 3
2: Premature end of data in tag PDFREPORT line 3
3: Premature end of data in tag PDFREPORTs line 3
4: Premature end of data in tag REPORT line 1

>ax1 ax1
a1$filedata <- sub("<PDFREPORT1>.*</PDFREPORT1>", "", a1$FILE_DATA)

> ax1 <- xmlParse(a1$filedata[[1]], asText = TRUE)
Premature end of data in tag PDFREPORT1 line 3
Premature end of data in tag PDFREPORT line 3
Premature end of data in tag PDFREPORTs line 3
Premature end of data in tag REPORT line 1
Error: 1: Premature end of data in tag PDFREPORT1 line 3
2: Premature end of data in tag PDFREPORT line 3
3: Premature end of data in tag PDFREPORTs line 3
4: Premature end of data in tag REPORT line 1