fix(vm): clear error when fetching field from string at runtime#963
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antonmedv merged 1 commit intoMay 26, 2026
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When a map value resolves to a string at runtime and is followed by a named-field access (e.g. v.k.missing where v.k is a string), the Fetch helper falls into the Array/Slice/String branch and calls ToInt on the field name. ToInt panics with "invalid operation: int(string)", which is confusing. Guard the branch: if the index is a string it can only be a property name, not an integer index, so panic with the canonical "cannot fetch <field> from <type>" message instead. Fixes expr-lang#962. Signed-off-by: Sai Asish Y <say.apm35@gmail.com>
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When a map value resolves to a string at runtime and is followed by a named-field access (e.g.
v.k.missingwherev.kis a string), theFetchhelper falls into theArray/Slice/Stringbranch and callsToInton the field name.ToIntpanics withinvalid operation: int(string), which is confusing for users expectingtype string has no field X.Guard the branch: if the index is a string it can only be a property name, not an integer index, so panic with the canonical
cannot fetch <field> from <type>message.Fixes #962.