wasmerio/wasmer · error

getting invalid type from table, handle this error

Error message

getting invalid type from table, handle this error

What it means

Table::get reads the raw table element and matches on the table's declared ValType; only ExternRef and FuncRef are handled. Any other ValType (should be impossible for a reference table) hits `todo!` — a defensive panic meant to be replaced with a proper error if invalid table types ever occur.

Source

Thrown at lib/vm/src/table.rs:245

        // update table definition
        unsafe {
            let mut td_ptr = self.get_vm_table_definition();
            let td = td_ptr.as_mut();
            td.current_elements = new_len;
            td.base = self.vec.as_mut_ptr() as _;
        }
        Some(size)
    }

    /// Get reference to the specified element.
    ///
    /// Returns `None` if the index is out of bounds.
    pub fn get(&self, index: u32) -> Option<TableElement> {
        let raw_data = self.vec.get(index as usize).cloned()?;
        Some(match self.table.ty {
            ValType::ExternRef => TableElement::ExternRef(unsafe { raw_data.extern_ref }),
            ValType::FuncRef => TableElement::FuncRef(unsafe { raw_data.func_ref }),
            _ => todo!("getting invalid type from table, handle this error"),
        })
    }

    /// Set reference to the specified element.
    ///
    /// # Errors
    ///
    /// Returns an error if the index is out of bounds.
    pub fn set(&mut self, index: u32, reference: TableElement) -> Result<(), Trap> {
        self.set_with_construction(index, reference, false)
    }

    pub(crate) fn set_with_construction(
        &mut self,
        index: u32,
        reference: TableElement,
        in_construction: bool,
    ) -> Result<(), Trap> {

View on GitHub (pinned to 8c4b9ee9d3)

Solutions

1. Only create tables via validated wasm or with Type limited to funcref/externref element types
2. Replace the todo! with a returned error/internal assertion so misuse surfaces as TableError instead of a panic
3. Audit embedder code that constructs Table/Type manually and fix the element ValType
4. Upgrade wasmer if a newly supported reference type needs handling here

Example fix

// before
_ => todo!("getting invalid type from table, handle this error"),
// after
_ => return None, // or record unreachable: tables may only hold references

// validate table element type before creating/accessing
fn table_type_is_reference(ty: &ValType) -> bool {
    matches!(ty, ValType::ExternRef | ValType::FuncRef)
}

fn elem_type_ok(table_type: &TableType) -> bool {
    matches!(table_type.ty, ValType::ExternRef | ValType::FuncRef)
}

// Table::get panics rather than returning Result; wrap table creation instead
let table = Table::new(store, TableType { ty: ValType::FuncRef, ..ty })?; // validated upstream
// then get() can only see FuncRef/ExternRef

When it happens

Trigger: Calling Table::get (directly or via table.copy's copy_within) on a table whose `table.ty` is neither ExternRef nor FuncRef, or on a table whose type descriptor got corrupted/misinitialized so the ValType match falls through.

Common situations: Embedders constructing tables programmatically (via Table::new with a Type carrying an unexpected ValType) rather than through wasm validation; fuzzing or memory corruption producing an out-of-contract table type; a wasmer version where table types were extended without updating this match.

Related errors

• unimplemented operator {operator:?}
• global #{} is a constant
• Cannot load reference type
• Unhandled inner case
• ref.is_null only accepts reference types

AI-assisted analysis of wasmerio/wasmer@8c4b9ee9d3 (2026-09-01). Data as JSON: /api/errors/5b82253165b9b88f. Report an issue: GitHub.