const customDeepMergeOptions: Options = {
    isMergeableObject: function newIsMergeableObject(value): boolean {
        // Default Logic from the Base Options it's not inheritable.
        return typeof value === 'object' && value !== null && !(value instanceof RegExp) && !(value instanceof Date)
            // Custom Overrides
            && !(value instanceof FormData);
    }
}

import deepmerge, { Options,  isMergeableObject} from "deepmerge";
const customDeepMergeOptions: Options = {
    isMergeableObject: function newIsMergeableObject(value): boolean {
        // Default Logic .
        return isMergeableObject(value) 
            // Custom Overrides
            && !(value instanceof FormData);
    }
}