When rendering JSONB back into text JSON, report an error if a zero-length

When rendering JSONB back into text JSON, report an error if a zero-length
integer or floating-point node is encountered.  Otherwise, if the node occurs
at the very end of the JSONB, the rendering logic might read one byte past
the end of the initialized part of the BLOB byte array.  OSSFuzz 66284.

FossilOrigin-Name: b0eb279ea83c1c788c39fb90e178ec99fa4c782195c376a420c661fedf4545a7