erroneous spans when an error is created with err_and_pop

[lrlna]

Our error spans are inconsistent when an error is created with err_and_pop.

A few examples.
GraphQL:

cats
# comment

Document:

- DOCUMENT@0..10
    - WHITESPACE@0..1 "\n"
    - COMMENT@1..10 "# comment"
- ERROR@0:4 "expected definition" cats

GraphQL:

cats

type Query {
    name: String
}

Document:

- DOCUMENT@0..33
    - WHITESPACE@0..2 "\n\n"
    - OBJECT_TYPE_DEFINITION@2..33
        - type_KW@2..6 "type"
        - WHITESPACE@6..7 " "
        - NAME@7..13
            - IDENT@7..12 "Query"
            - WHITESPACE@12..13 " "
        - FIELDS_DEFINITION@13..33
            - L_CURLY@13..14 "{"
            - WHITESPACE@14..19 "\n    "
            - FIELD_DEFINITION@19..32
                - NAME@19..23
                    - IDENT@19..23 "name"
                - COLON@23..24 ":"
                - WHITESPACE@24..25 " "
                - NAMED_TYPE@25..31
                    - NAME@25..31
                        - IDENT@25..31 "String"
                - WHITESPACE@31..32 "\n"
            - R_CURLY@32..33 "}"
- ERROR@0:4 "expected definition" cats

This no longer becomes the case when the error precedes a valid statement, so if we reverse the two statements above:

type Query {
    name: String
}

cats

Our Document's spans are then correct:

- DOCUMENT@0..33
    - OBJECT_TYPE_DEFINITION@0..33
        - type_KW@0..4 "type"
        - WHITESPACE@4..5 " "
        - NAME@5..11
            - IDENT@5..10 "Query"
            - WHITESPACE@10..11 " "
        - FIELDS_DEFINITION@11..33
            - L_CURLY@11..12 "{"
            - WHITESPACE@12..17 "\n    "
            - FIELD_DEFINITION@17..30
                - NAME@17..21
                    - IDENT@17..21 "name"
                - COLON@21..22 ":"
                - WHITESPACE@22..23 " "
                - NAMED_TYPE@23..29
                    - NAME@23..29
                        - IDENT@23..29 "String"
                - WHITESPACE@29..30 "\n"
            - R_CURLY@30..31 "}"
            - WHITESPACE@31..33 "\n\n"
- ERROR@33:37 "expected definition" cats

Initially found in #324

[goto-bus-stop]

Closing this in favour of follow-ups: #450 and #451