The following error is thrown: ‘SSS_FILE_CONTENT_SIZE_EXCEEDED: The file content you are attempting to access exceeds the maximum allowed size of 10 MB’ for SuiteScript 1.0.
This is a known error that is thrown if a file larger than 10 MB is uploaded via nlapiLoadFile() and its contents are read using any of the following methods:
nlobjFile.getValue()
JSON.stringify()
To summarize, this is an expected behavior. Also note that loading a file larger than 10 MB using nlapiLoadFile() alone will not throw the error.