Can’t use @import inside each()

Have this piece of code that imports component files based on a variable.

@components: {
    columns: true;
    ratios: false;
};

each(@components, {
    & when (@value = true) {
        @import "components/@{key}.less";
    }
});

It errors, with: error evaluating function 'each': variable @key is undefined.

But it is defined, because this works:

// LESS
each(@components, {
    & when (@value = true) {
        .test {
            content: @key;
        }
    }
});

// CSS Output
.test {
    content: columns;
}

It’s not due to the variable being a map, or the usage of a guard, this example using a list creates the same error:

each(@components, {
  @import "components/@{value}.less";
});

Is there an alternative way to achieve this?

No source file or test is named. Reproduce the map and list examples in the Less compiler, then trace how each() bindings are handled when an @import path is evaluated. Done means the reported behavior has a regression test and the supported outcome is clear.