Major Description
User reports that an expression xs:unsignedInt(str) where the str contains leading whitespace, fails with:
Unparse Error: Cannot convert ' 0' from String type to Long (Cannot conert to type long: for input string: " 0")
Note that this is an unparse error.
The XPath specification says that when converting from string to other atomic simple types, whitespace normalization applies, which trims leading and trailing whitespace. So this should not fail.