Mutable operations vs dynamic checks with `RefCell`

[raviqqe]

• Or, potentially unsafe silent mutability?

melior/melior/src/ir/block.rs

Line 129 in f83d518

pub fn insert_operation(

melior/melior/src/ir/block.rs

Line 116 in f83d518

pub fn append_operation(&self, operation: Operation<'c>) -> OperationRef<'c, '_> {