XPath silently ignores erroneous evaluation where a nodeset is required

[tompng]

In XPath evaluation, some evaluated part is required to be a nodeset. If not, it should result in error.
#342 (comment)

Examples:

# Function argument that requires nodeset
local-name(1)
sum("string")
count(1 < 2)

# Path after function that doesn't return a nodeset
# id("a")/path id("a")[predicate] is valid
string(a/b)[predicate]
string(a/b)/path

# Path after non-nodeset variable
$x[predicate]
$x/path

# Path after literal
"string"[predicate]
42/path

# Path after neg
-number(a/b)[predicate]
-number(a/b)/path

# Path after parenthesized expression
(1)[predicate]
(1)/path